Mid 2011 rebooting by itself

Question

I have a mid-2011 iMac (2.8GHz i7, 8GB RAM) with a recent installation of Yosemite. I have now had two occurrences where the machine has spontaneously rebooted - both seem to be sleep/hibernate related, though a search of the literature hasn't turned up too many suggestions that seem to lead me anywhere. Here's an extract of the system logs based in Linc's script; also happy to pull anything else out.
Start time: 15:37:58 03/05/15
Revision: 1241
Model Identifier: iMac12,1
System Version: OS X 10.10.2 (14C109)
Kernel Version: Darwin 14.1.0
Time since boot: 1:12
UID: 501
SerialATA
    ST31000528AS                           
USB
    CRCA102#BJ1 (Cyber Power Systems, Inc.)
    USB Audio CODEC (Texas Instruments Japan)
Bluetooth
    Apple Wireless Trackpad
    Apple Wireless Keyboard
System errors (per sec)
    Google Chrome H (UID 501, error 35): 130
    Google Chrome (UID 501, error 35): 101
Firewall: On
Listeners
    kdc: kerberos
    launchd: afpovertcp
    launchd: microsoft-ds
    launchd: ssh
Diagnostic reports
    2015-02-11 garcon crash
    2015-02-17 Splashtop Personal hang
    2015-02-17 mdworker32 crash x2
    2015-02-23 garcon crash
    2015-02-24 FindSystemFiles crash
    2015-02-27 Finder hang
    2015-03-05 Finder hang
Kernel log
    Mar  3 23:09:51 AFP_VFS afpfs_DoReconnect:  Primary Reconnect failed 5 on /Volumes/Backups
    Mar  3 23:10:49 32311.775815: setPOWERSAVE ****SYNC SCAN CANCEL FAILED 
    Mar  4 08:29:58 Failed to get hibernate image filename
    Mar  4 10:34:49 Failed to get hibernate image filename
    Mar  4 12:27:55 Failed to get hibernate image filename
    Mar  4 13:26:26 Failed to get hibernate image filename
    Mar  4 14:23:38 Failed to get hibernate image filename
    Mar  4 16:00:47 Limiting closed port RST response from 440 to 250 packets per second
    Mar  4 16:04:48 Limiting closed port RST response from 396 to 250 packets per second
    Mar  4 16:05:02 Limiting closed port RST response from 387 to 250 packets per second
    Mar  4 16:44:40 Failed to get hibernate image filename
    Mar  4 19:12:47 Limiting closed port RST response from 290 to 250 packets per second
    Mar  4 19:34:43 Failed to get hibernate image filename
    Mar  4 21:09:16 Failed to get hibernate image filename
    Mar  4 22:28:56 Failed to get hibernate image filename
    Mar  5 06:39:37 Failed to get hibernate image filename
    Mar  5 09:43:29 Failed to get hibernate image filename
    Mar  5 11:57:14 Failed to get hibernate image filename
    Mar  5 13:32:18 Failed to get hibernate image filename
    Mar  5 14:20:35 Failed to get hibernate image filename
    Mar  5 14:26:52 Sleep failure code 0x00000040 0x14006900
    Mar  5 14:26:52 System was rebooted due to Sleep/Wake failure
    Mar  5 14:26:53 ** GPU Hardware VM is disabled (multispace: disabled, page table updates with DMA: disabled)
    Mar  5 14:42:28 Failed to get hibernate image filename
    Mar  5 15:27:06 Failed to get hibernate image filename
System log
        label = "2.5.4.6";
        "localized label" = "2.5.4.6";
        type = string;
        value = US;
        label = "2.5.4.8";
        "localized label" = "2.5.4.8";
        type = string;
        value = California;
        label = "2.5.4.7";
        "localized label" = "2.5.4.7";
        type = string;
        value = Cupertino;
        label = "2.5.4.10";
        "localized label" = "2.5.4.10";
        type = string;
        value = "Apple Inc.";
        label = "2.5.4.3";
        "localized label" = "2.5.4.3";
        type = string;
        value = "courier.sandbox.push.apple.com";
Console log
    Feb 27 08:04:05 nsurlstoraged realpath() returned NULL for /Users/USER/Library/Caches/com.apple.icloud.fmfd
    Feb 27 08:04:05 nsurlstoraged The read-connection to the DB=/Users/USER/Library/Caches/com.apple.icloud.fmfd/Cache.db is NOT valid.  Unable to determine schema version.
    Feb 27 08:04:05 nsurlstoraged realpath() returned NULL for /Users/USER/Library/Caches/com.apple.icloud.fmfd
    Feb 27 08:04:05 nsurlstoraged realpath() returned NULL for /Users/USER/Library/Caches/com.apple.icloud.fmfd
    Feb 27 08:04:09 nsurlstoraged realpath() returned NULL for /Users/USER/Library/Caches/com.apple.icloud.fmfd
    Feb 27 08:04:14 nsurlstoraged realpath() returned NULL for /Users/USER/Library/Caches/com.apple.icloud.fmfd
    Feb 27 08:05:12 ReportCrash Invoking spindump for pid=248 wakeups_rate=542 duration=84 because of excessive wakeups
    Feb 28 06:38:59 nsurlstoraged realpath() returned NULL for /Users/USER/Library/Caches/com.apple.icloud.fmfd
    Mar  4 20:51:19 ReportCrash Invoking spindump for pid=4914 wakeups_rate=190 duration=237 because of excessive wakeups
    Mar  4 22:04:11 ReportCrash Invoking spindump for pid=249 thread=4856 percent_cpu=56 duration=161 because of excessive cpu utilization
    Mar  5 11:32:58 ReportCrash Invoking spindump for pid=5203 wakeups_rate=168 duration=268 because of excessive wakeups
    Mar  5 14:54:26 nsurlstoraged realpath() returned NULL for /Users/USER/Library/Caches/com.apple.icloud.fmfd
    Mar  5 14:54:26 nsurlstoraged The read-connection to the DB=/Users/USER/Library/Caches/com.apple.icloud.fmfd/Cache.db is NOT valid.  Unable to determine schema version.
    Mar  5 14:54:26 nsurlstoraged realpath() returned NULL for /Users/USER/Library/Caches/com.apple.icloud.fmfd
    Mar  5 14:54:26 nsurlstoraged realpath() returned NULL for /Users/USER/Library/Caches/com.apple.icloud.fmfd
    Mar  5 14:54:29 nsurlstoraged realpath() returned NULL for /Users/USER/Library/Caches/com.apple.icloud.fmfd
    Mar  5 14:54:35 nsurlstoraged realpath() returned NULL for /Users/USER/Library/Caches/com.apple.icloud.fmfd
    Mar  5 14:55:44 ReportCrash Invoking spindump for pid=279 wakeups_rate=536 duration=84 because of excessive wakeups
Daemons
    com.apple.Kerberos.kdc
    - status: 1
    com.apple.watchdogd
    com.bjango.istatmenusdaemon
    com.google.keystone.daemon
    com.microsoft.office.licensing.helper
    com.timesoftware.timemachineeditor.backup-auto
    com.timesoftware.timemachineeditor.helper
Agents
    2BUA8C4S2C.com.agilebits.onepassword4-helper
    com.apple.AirPortBaseStationAgent
    com.apple.photostream-agent
    com.bjango.istatmenusagent
    com.bjango.istatmenusnotifications
    com.google.keystone.system.agent
User login items
    iTunesHelper
    - /Applications/iTunes.app/Contents/MacOS/iTunesHelper.app
    Dropbox
    - /Applications/Dropbox.app
    BetterSnapTool
    - /Applications/BetterSnapTool.app
User crontab
    0 6,18 * * * curl -o /dev/null --user uuuuuuuu:pppppppp https://dynamic.zoneedit.com/auth/dynamic.html?host=myhost.mydomain.com > /dev/null
Widgets
    App Update
    Delivery Status
    PEMDAS
iCloud errors
    bird 57
    cloudd 29
    CallHistorySyncHelper 1
Restricted files: 71
Contents of /Library/LaunchAgents/com.bjango.istatmenusagent.plist
    - mod date: Jan 27 13:43:40 2015
    - checksum: 1701899968
    <?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
    <plist version="1.0">
    <dict>
    <key>LimitLoadToSessionType</key>
    <string>Aqua</string>
    <key>KeepAlive</key>
    <true/>
    <key>Label</key>
    <string>com.bjango.istatmenusagent</string>
    <key>Program</key>
    <string>/Library/Application Support/iStat Menus 5/iStatMenusAgent.app/Contents/MacOS/iStatMenusAgent</string>
    <key>RunAtLoad</key>
    <true/>
    </dict>
    </plist>
Contents of /Library/LaunchAgents/com.bjango.istatmenusnotifications.plist
    - mod date: Jan 27 13:43:40 2015
    - checksum: 3879995847
    <?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
    <plist version="1.0">
    <dict>
    <key>LimitLoadToSessionType</key>
    <string>Aqua</string>
    <key>KeepAlive</key>
    <true/>
    <key>Label</key>
    <string>com.bjango.istatmenusnotifications</string>
    <key>Program</key>
    <string>/Library/Application Support/iStat Menus 5/iStat Menus Notifications.app/Contents/MacOS/iStat Menus Notifications</string>
    <key>RunAtLoad</key>
    <true/>
    </dict>
    </plist>
Contents of /Library/LaunchDaemons/com.bjango.istatmenusdaemon.plist
    - mod date: Jan 27 13:43:40 2015
    - checksum: 3935573610
    <?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
    <plist version="1.0">
    <dict>
    <key>KeepAlive</key>
    <true/>
    <key>Label</key>
    <string>com.bjango.istatmenusdaemon</string>
    <key>Program</key>
    <string>/Library/Application Support/iStat Menus 5/iStatMenusDaemon</string>
    <key>RunAtLoad</key>
    <true/>
    </dict>
    </plist>
Contents of /Library/LaunchDaemons/com.timesoftware.timemachineeditor.backup-auto.plist
    - mod date: Feb 12 07:52:44 2015
    - checksum: 530410832
    <?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
    <plist version="1.0">
    <dict>
    <key>Label</key>
    <string>com.timesoftware.timemachineeditor.backup-auto</string>
    <key>ProgramArguments</key>
    <array>
    <string>/Library/PrivilegedHelperTools/com.timesoftware.timemachineeditor.helpe r</string>
    <string>--backup</string>
    </array>
    <key>StartCalendarInterval</key>
    <dict>
    <key>Hour</key>
    <integer>1</integer>
    <key>Minute</key>
    <integer>0</integer>
    </dict>
    </dict>
    </plist>
Contents of /Library/LaunchDaemons/com.timesoftware.timemachineeditor.helper.plist
    - mod date: Jan 29 12:49:52 2015
    - checksum: 933387316
    <?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
    <plist version="1.0">
    <dict>
    <key>Label</key>
    <string>com.timesoftware.timemachineeditor.helper</string>
    <key>MachServices</key>
    <dict>
    <key>com.timesoftware.timemachineeditor.helper</key>
    <true/>
    </dict>
    <key>Program</key>
    <string>/Library/PrivilegedHelperTools/com.timesoftware.timemachineeditor.helpe r</string>
    <key>ProgramArguments</key>
    <array>
    <string>/Library/PrivilegedHelperTools/com.timesoftware.timemachineeditor.helpe r</string>
    </array>
    </dict>
    </plist>
Contents of /System/Library/Security/authorization.plist
    - mod date: Oct  9 02:17:00 2014
    - checksum: 2720110640
    <?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
    <plist version="1.0">
    <dict>
    <key>comment</key>
    <string>The name of the requested right is matched against the keys.  An exact match has priority, otherwise the longest match from the start is used. Note that the right will only match wildcard rules (ending in a ".") during this reduction.
    allow rule: this is always allowed
    &lt;key&gt;com.apple.TestApp.benign&lt;/key&gt;
    &lt;string&gt;allow&lt;/string&gt;
    deny rule: this is always denied
    &lt;key&gt;com.apple.TestApp.dangerous&lt;/key&gt;
    &lt;string&gt;deny&lt;/string&gt;
    user rule: successful authentication as a user in the specified group(5) allows the associated right.
    The shared property specifies whether a credential generated on success is shared with other apps (i.e., those in the same "session"). This property defaults to false if not specified.
    The timeout property specifies the maximum age of a (cached/shared) credential accepted for this rule.
    The allow-root property specifies whether a right should be allowed automatically if the requesting process is running with uid == 0.  This defaults to false if not specified.
    See remaining rules for examples.
    </string>
    <key>rights</key>
    <dict>
    <key></key>
    <dict>
    <key>class</key>
    <string>rule</string>
    <key>comment</key>
    ...and 1850 more line(s)
Applications
    /Applications/ACSLogo/ACSLogo.app
    - com.acsmith.acslogo
    /Applications/Carbon Copy Cloner.app
    - com.bombich.ccc
    /Applications/Crayon Physics Deluxe.app
    - com.yourcompany.Crayon
    /Applications/H&R Block 2009.app
    - com.hrblock.tax.2009
    /Applications/H&R Block 2010.app
    - com.hrblock.tax.2010
    /Applications/H&R Block 2011.app
    - com.hrblock.tax.2011
    /Applications/HandBrake.app
    - fr.handbrake.HandBrake
    /Applications/Microsoft Messenger.app
    - com.microsoft.Messenger
    /Applications/Microsoft Office 2011/Office/Add-Ins/Solver.app
    - com.microsoft.ASApplication
    /Applications/Microsoft Office 2011/Office/Equation Editor.app
    - com.microsoft.EquationEditor
    /Applications/Microsoft Office 2011/Office/Microsoft Office Setup Assistant.app
    - com.microsoft.office.setupassistant
    /Applications/Microsoft Office 2011/Office/Microsoft Query.app
    - com.microsoft.Query
    /Applications/Remote Desktop Connection.app
    - com.microsoft.rdc
    /Library/Application Support/Script Editor/Templates/Cocoa-AppleScript Applet.app
    - com.apple.ScriptEditor.id.cocoa-applet-template
    /Library/Application Support/Script Editor/Templates/Droplets/Droplet with Settable Properties.app
    - com.apple.ScriptEditor.id.droplet-with-settable-properties-template
    /Library/Application Support/Script Editor/Templates/Droplets/Recursive File Processing Droplet.app
    - com.apple.ScriptEditor.id.file-processing-droplet-template
    /Library/Application Support/Script Editor/Templates/Droplets/Recursive Image File Processing Droplet.app
    - com.apple.ScriptEditor.id.image-file-processing-droplet-template
    /Library/Application Support/iStat Menus 5/iStat Menus Notifications.app
    - com.bjango.iStat-Menus-Notifications
    /Library/Application Support/iStat Menus 5/iStatMenusAgent.app
    - com.bjango.iStatMenusAgent
    /Users/USER/Applications/Chrome Apps.localized/Default iabmpiboiopbgfabjmgeedhcmjenhbla.app:® Viewer for Google Chrome™:
    - N/A
    /Users/USER/Documents/Parallels/Windows 7.pvm/Windows 7.app
    - com.parallels.winapp.UUID.UUID.fs
    /Users/USER/Downloads/Aquaria.app
    - com.bit-blot.aquaria
    /Users/USER/Downloads/DEFCON.app
    - uk.co.introversion.Defcon
    /Users/USER/Downloads/Darwinia.app
    - uk.co.darwinia
    /Users/USER/Downloads/mule.app
    - N/A
    /Users/USER/Library/Application Support/Google/Chrome/Default/Web Applications/_crx_aapocclcgogkmnckokdopfmhonfmgoek/Default aapocclcgogkmnckokdopfmhonfmgoek.app
    - com.google.Chrome.app.Default-aapocclcgogkmnckokdopfmhonfmgoek-internal
    /Users/USER/Library/Application Support/Google/Chrome/Default/Web Applications/_crx_aohghmighlieiainnegkcijnfilokake/Default aohghmighlieiainnegkcijnfilokake.app
    - com.google.Chrome.app.Default-aohghmighlieiainnegkcijnfilokake-internal
    /Users/USER/Library/Application Support/Google/Chrome/Default/Web Applications/_crx_apdfllckaahabafndbhieahigkjlhalf/Default apdfllckaahabafndbhieahigkjlhalf.app
    - com.google.Chrome.app.Default-apdfllckaahabafndbhieahigkjlhalf-internal
    /Users/USER/Library/Application Support/Google/Chrome/Default/Web Applications/_crx_blpcfgokakmgnkcojhhkbfbldkacnbeo/Default blpcfgokakmgnkcojhhkbfbldkacnbeo.app
    - com.google.Chrome.app.Default-blpcfgokakmgnkcojhhkbfbldkacnbeo-internal
    /Users/USER/Library/Application Support/Google/Chrome/Default/Web Applications/_crx_coobgpohoikkiipiblmjeljniedjpjpf/Default coobgpohoikkiipiblmjeljniedjpjpf.app
    - com.google.Chrome.app.Default-coobgpohoikkiipiblmjeljniedjpjpf-internal
    /Users/USER/Library/Application Support/Google/Chrome/Default/Web Applications/_crx_felcaaldnbdncclmgdcncolpebgiejap/Default felcaaldnbdncclmgdcncolpebgiejap.app
    - com.google.Chrome.app.Default-felcaaldnbdncclmgdcncolpebgiejap-internal
    /Users/USER/Library/Application Support/Google/Chrome/Default/Web Applications/_crx_gbchcmhmhahfdphkhkmpfmihenigjmpp/Default gbchcmhmhahfdphkhkmpfmihenigjmpp.app
    - com.google.Chrome.app.Default-gbchcmhmhahfdphkhkmpfmihenigjmpp-internal
    /Users/USER/Library/Application Support/Google/Chrome/Default/Web Applications/_crx_iabmpiboiopbgfabjmgeedhcmjenhbla/Default iabmpiboiopbgfabjmgeedhcmjenhbla.app:® Viewer for Google Chrome™:
    - N/A
    /Users/USER/Library/Application Support/Google/Chrome/Default/Web Applications/_crx_nmmhkkegccagdldgiimedpiccmgmieda/Default nmmhkkegccagdldgiimedpiccmgmieda.app
    - com.google.Chrome.app.Default-nmmhkkegccagdldgiimedpiccmgmieda-internal
    /Users/USER/Library/Application Support/Google/Chrome/Default/Web Applications/_crx_pjkljhegncpnkpknbcohdijeoejaedia/Default pjkljhegncpnkpknbcohdijeoejaedia.app
    - com.google.Chrome.app.Default-pjkljhegncpnkpknbcohdijeoejaedia-internal
Bundles
    /Library/Internet Plug-Ins/SharePointBrowserPlugin.plugin
    - com.microsoft.sharepoint.browserplugin
    /Users/USER/Library/Widgets/App Update.wdgt
    - com.gck.app_update_widget
    /Users/USER/Library/Widgets/CBSNews.com Breaking News.wdgt
    - com.cbsnews.breakingNews
    /Users/USER/Library/Widgets/Delivery Status.wdgt
    - com.junecloud.widget.deliverystatus
    /Users/USER/Library/Widgets/PEMDAS.wdgt
    - com.donkeyentertainment.widget.PEMDAS
Bundles (new)
    /Users/USER/Library/Application Support/Google/Chrome/Default/Web Applications/_crx_nmmhkkegccagdldgiimedpiccmgmieda/Default nmmhkkegccagdldgiimedpiccmgmieda.app
    - com.google.Chrome.app.Default-nmmhkkegccagdldgiimedpiccmgmieda-internal
    /Users/USER/Library/Application Support/Google/Chrome/Default/Web Applications/_crx_pjkljhegncpnkpknbcohdijeoejaedia/Default pjkljhegncpnkpknbcohdijeoejaedia.app
    - com.google.Chrome.app.Default-pjkljhegncpnkpknbcohdijeoejaedia-internal
Library paths
    /Applications/Microsoft Office 2011/Office/MicrosoftSetupUI.framework/Libraries/mbupgx.dylib
    /Applications/Microsoft Office 2011/Office/OPF.framework/Versions/14/Resources/OPF_Common.dylib
    /Applications/Microsoft Office 2011/Office/Visual Basic for Applications.framework/Versions/14/Frameworks/Fm20.dylib
    /Applications/Microsoft Office 2011/Office/Visual Basic for Applications.framework/Versions/14/Frameworks/MicrosoftOLE2TypesLib.dylib
    /Applications/Microsoft Office 2011/Office/Visual Basic for Applications.framework/Versions/14/Frameworks/RefEdit.dylib
    /Applications/Microsoft Office 2011/Office/Visual Basic for Applications.framework/Versions/14/Frameworks/RichEdit.dylib
    /Users/USER/Library/Application Support/Google/Chrome/WidevineCDM/1.4.7.771/_platform_specific/mac_x64/libwidev inecdm.dylib
App extensions
    com.getdropbox.dropbox.garcon
    com.pixelmatorteam.pixelmator.Repair-Tool-Action-Extension
Installations
    Microsoft Office for Mac 2011: 1/27/15, 3:16 PM
    Splashtop 2: 1/27/15, 1:41 PM
    Liquid Legacy: 1/27/15, 1:39 PM
    Pixelmator: 1/27/15, 1:38 PM
    BetterSnapTool: 1/27/15, 1:36 PM
Elapsed time (sec): 224

Answer 1

I don't recommend posting the output of that script unless asked to do so by me, as I can't vouch for what kind of advice you may get from others. That said, there was a recall program (now ended, apparently) for that model because of defective hard drives. That or some other hardware fault is the likely cause of your problem. Take the machine to an Apple Store for testing.