"Panic" Crash, help please...

Question

I'm getting a panic crash/restart every day or so lately. Here's the report from the most recent one:
Any help in resolving this would be greatly appreciated!!
Interval Since Last Panic Report:  1982921 sec
Panics Since Last Report:          3
Anonymous UUID:                    0E5FCEE2-4388-7BC0-5A86-6A0A2DA22B5C
Wed Feb 27 15:31:23 2013
panic(cpu 2 caller 0xffffff8021843d8e): "a freed zone element has been modified in zone: kalloc.16"@/SourceCache/xnu/xnu-2050.18.24/osfmk/kern/zalloc.c:219
Backtrace (CPU 2), Frame : Return Address
0xffffff8111af3b10 : 0xffffff802181d626
0xffffff8111af3b80 : 0xffffff8021843d8e
0xffffff8111af3bc0 : 0xffffff80218435d2
0xffffff8111af3ca0 : 0xffffff80218245ed
0xffffff8111af3cd0 : 0xffffff8021c038b1
0xffffff8111af3cf0 : 0xffffff8021c039f2
0xffffff8111af3d20 : 0xffffff8021c01eb3
0xffffff8111af3d70 : 0xffffff8021c03ca3
0xffffff8111af3da0 : 0xffffff8021bf20a1
0xffffff8111af3de0 : 0xffffff8021c27c23
0xffffff8111af3e00 : 0xffffff8021c321e1
0xffffff8111af3e10 : 0xffffff8021c63b28
0xffffff8111af3e50 : 0xffffff8021893f72
0xffffff8111af3e80 : 0xffffff8021820aed
0xffffff8111af3eb0 : 0xffffff8021810448
0xffffff8111af3f00 : 0xffffff802181961b
0xffffff8111af3f70 : 0xffffff80218a5b16
0xffffff8111af3fb0 : 0xffffff80218ced53
BSD process name corresponding to current thread: SystemUIServer
Mac OS version:
12C60
Kernel version:
Darwin Kernel Version 12.2.0: Sat Aug 25 00:48:52 PDT 2012; root:xnu-2050.18.24~1/RELEASE_X86_64
Kernel UUID: 69A5853F-375A-3EF4-9247-478FD0247333
Kernel slide:     0x0000000021600000
Kernel text base: 0xffffff8021800000
System model name: MacBookPro8,2 (Mac-94245A3940C91C80)
System uptime in nanoseconds: 190782484104117
last loaded kext at 190599884007237: com.sophos.kext.sav          8.0.4 (addr 0xffffff7fa3ce0000, size 24576)
last unloaded kext at 190597681818159: com.sophos.kext.sav          8.0.4 (addr 0xffffff7fa3c64000, size 20480)
loaded kexts:
com.sophos.kext.sav          8.0.4
com.Logitech.Unifying.HID Driver          1.2.0
jp.plentycom.driver.SteerMouse          4.1.5
com.Logitech.Control Center.HID Driver          3.6.0
com.apple.driver.Oxford_Semi          3.1.0
com.apple.filesystems.afpfs          10.0
com.apple.nke.asp_tcp          7.0.0
com.apple.driver.AppleHWSensor          1.9.5d0
com.apple.driver.AudioAUUC          1.60
com.apple.driver.AGPM          100.12.69
com.apple.driver.AppleMikeyHIDDriver          122
com.apple.iokit.IOUserEthernet          1.0.0d1
com.apple.driver.AppleUSBDisplays          353
com.apple.kext.AMDFramebuffer          8.0.0
com.apple.driver.AppleHDA          2.3.1f2
com.apple.driver.AppleMikeyDriver          2.3.1f2
com.apple.iokit.IOBluetoothSerialManager          4.0.9f33
com.apple.driver.AppleUpstreamUserClient          3.5.10
com.apple.filesystems.autofs          3.0
com.apple.iokit.BroadcomBluetoothHCIControllerUSBTransport          4.0.9f33
com.apple.AMDRadeonAccelerator          1.0.0
com.apple.Dont_Steal_Mac_OS_X          7.0.0
com.apple.driver.AppleSMCLMU          2.0.2d0
com.apple.driver.AppleSMCPDRC          1.0.0
com.apple.driver.AppleLPC          1.6.0
com.apple.driver.ApplePolicyControl          3.2.11
com.apple.driver.AppleMuxControl          3.2.11
com.apple.driver.ACPI_SMC_PlatformPlugin          1.0.0
com.apple.driver.AppleIntelHD3000Graphics          8.0.0
com.apple.driver.AppleIntelSNBGraphicsFB          8.0.0
com.apple.driver.SMCMotionSensor          3.0.2d6
com.apple.driver.AppleMCCSControl          1.0.33
com.apple.driver.AppleUSBTCButtons          235.4
com.apple.driver.AppleUSBTCKeyboard          235.4
com.apple.driver.AppleIRController          320.15
com.apple.AppleFSCompression.AppleFSCompressionTypeDataless          1.0.0d1
com.apple.AppleFSCompression.AppleFSCompressionTypeZlib          1.0.0d1
com.apple.BootCache          34
com.apple.iokit.SCSITaskUserClient          3.5.1
com.apple.driver.XsanFilter          404
com.apple.iokit.IOAHCIBlockStorage          2.2.2
com.apple.driver.AppleUSBHub          5.2.5
com.apple.driver.AirPort.Brcm4331          602.15.22
com.apple.driver.AppleSDXC          1.2.2
com.apple.iokit.AppleBCM5701Ethernet          3.2.5b3
com.apple.driver.AppleFWOHCI          4.9.6
com.apple.driver.AppleAHCIPort          2.4.1
com.apple.driver.AppleUSBEHCI          5.4.0
com.apple.driver.AppleEFINVRAM          1.6.1
com.apple.driver.AppleSmartBatteryManager          161.0.0
com.apple.driver.AppleACPIButtons          1.6
com.apple.driver.AppleRTC          1.5
com.apple.driver.AppleHPET          1.7
com.apple.driver.AppleSMBIOS          1.9
com.apple.driver.AppleACPIEC          1.6
com.apple.driver.AppleAPIC          1.6
com.apple.driver.AppleIntelCPUPowerManagementClient          196.0.0
com.apple.nke.applicationfirewall          4.0.39
com.apple.security.quarantine          2
com.apple.driver.AppleIntelCPUPowerManagement          196.0.0
com.apple.iokit.IOFireWireSerialBusProtocolTransport          2.1.1
com.apple.iokit.IOFireWireSBP2          4.2.0
com.apple.security.SecureRemotePassword          1.0
com.apple.iokit.IOSurface          86.0.3
com.apple.driver.DspFuncLib          2.3.1f2
com.apple.iokit.IOAudioFamily          1.8.9fc10
com.apple.kext.OSvKernDSPLib          1.6
com.apple.iokit.IOSerialFamily          10.0.6
com.apple.kext.triggers          1.0
com.apple.iokit.AppleBluetoothHCIControllerUSBTransport          4.0.9f33
com.apple.iokit.IOAcceleratorFamily          19.0.26
com.apple.iokit.IOFireWireIP          2.2.5
com.apple.driver.AppleSMBusPCI          1.0.10d0
com.apple.kext.AMD6000Controller          8.0.0
com.apple.kext.AMDSupport          8.0.0
com.apple.driver.AppleGraphicsControl          3.2.11
com.apple.driver.AppleHDAController          2.3.1f2
com.apple.iokit.IOHDAFamily          2.3.1f2
com.apple.driver.IOPlatformPluginLegacy          1.0.0
com.apple.driver.IOPlatformPluginFamily          5.2.0d16
com.apple.driver.AppleSMC          3.1.4d2
com.apple.driver.AppleBacklightExpert          1.0.4
com.apple.iokit.IONDRVSupport          2.3.5
com.apple.driver.AppleSMBusController          1.0.10d0
com.apple.iokit.IOGraphicsFamily          2.3.5
com.apple.iokit.IOSCSIBlockCommandsDevice          3.5.1
com.apple.iokit.IOUSBMassStorageClass          3.5.0
com.apple.driver.AppleThunderboltDPInAdapter          1.8.5
com.apple.driver.AppleThunderboltDPAdapterFamily          1.8.5
com.apple.driver.AppleThunderboltPCIDownAdapter          1.2.5
com.apple.driver.AppleUSBMultitouch          235.7
com.apple.driver.IOBluetoothHIDDriver          4.0.9f33
com.apple.iokit.IOBluetoothFamily          4.0.9f33
com.apple.iokit.IOUSBHIDDriver          5.2.5
com.apple.driver.AppleUSBMergeNub          5.2.5
com.apple.driver.AppleUSBComposite          5.2.5
com.apple.iokit.IOSCSIMultimediaCommandsDevice          3.5.1
com.apple.iokit.IOBDStorageFamily          1.7
com.apple.iokit.IODVDStorageFamily          1.7.1
com.apple.iokit.IOCDStorageFamily          1.7.1
com.apple.iokit.IOAHCISerialATAPI          2.5.0
com.apple.iokit.IOSCSIArchitectureModelFamily          3.5.1
com.apple.driver.AppleThunderboltNHI          1.6.0
com.apple.iokit.IOThunderboltFamily          2.1.1
com.apple.iokit.IOUSBUserClient          5.2.5
com.apple.iokit.IO80211Family          500.15
com.apple.iokit.IOEthernetAVBController          1.0.2b1
com.apple.iokit.IONetworkingFamily          3.0
com.apple.iokit.IOFireWireFamily          4.5.5
com.apple.iokit.IOAHCIFamily          2.2.1
com.apple.iokit.IOUSBFamily          5.4.0
com.apple.driver.AppleEFIRuntime          1.6.1
com.apple.iokit.IOHIDFamily          1.8.0
com.apple.iokit.IOSMBusFamily          1.1
com.apple.security.sandbox          220
com.apple.kext.AppleMatch          1.0.0d1
com.apple.security.TMSafetyNet          7
com.apple.driver.DiskImages          344
com.apple.iokit.IOStorageFamily          1.8
com.apple.driver.AppleKeyStore          28.21
com.apple.driver.AppleACPIPlatform          1.6
com.apple.iokit.IOPCIFamily          2.7.2
com.apple.iokit.IOACPIFamily          1.4
com.apple.kec.corecrypto          1.0
Model: MacBookPro8,2, BootROM MBP81.0047.B27, 4 processors, Intel Core i7, 2.4 GHz, 8 GB, SMC 1.69f4
Graphics: Intel HD Graphics 3000, Intel HD Graphics 3000, Built-In, 512 MB
Graphics: AMD Radeon HD 6770M, AMD Radeon HD 6770M, PCIe, 1024 MB
Memory Module: BANK 0/DIMM0, 4 GB, DDR3, 1333 MHz, 0x859B, 0x435435313236344243313333392E4D313646
Memory Module: BANK 1/DIMM0, 4 GB, DDR3, 1333 MHz, 0x859B, 0x435435313236344243313333392E4D313646
AirPort: spairport_wireless_card_type_airport_extreme (0x14E4, 0xD6), Broadcom BCM43xx 1.0 (5.106.98.81.22)
Bluetooth: Version 4.0.9f33 10885, 2 service, 18 devices, 1 incoming serial ports
Network Service: Wi-Fi, AirPort, en1
Serial ATA Device: APPLE HDD HTS727575A9E362, 750.16 GB
Serial ATA Device: MATSHITADVD-R   UJ-8A8
USB Device: hub_device, 0x0424  (SMSC), 0x2513, 0xfa100000 / 3
USB Device: Apple Internal Keyboard / Trackpad, apple_vendor_id, 0x0252, 0xfa120000 / 5
USB Device: BRCM2070 Hub, 0x0a5c  (Broadcom Corp.), 0x4500, 0xfa110000 / 4
USB Device: Bluetooth USB Host Controller, apple_vendor_id, 0x821a, 0xfa113000 / 7
USB Device: FaceTime HD Camera (Built-in), apple_vendor_id, 0x8509, 0xfa200000 / 2
USB Device: hub_device, 0x0424  (SMSC), 0x2513, 0xfd100000 / 2
USB Device: hub_device, apple_vendor_id, 0x1008, 0xfd120000 / 4
USB Device: USB2.0 Hub, 0x05e3  (Genesys Logic, Inc.), 0x0608, 0xfd121000 / 5
USB Device: HDD, 0x059b  (Iomega Corporation), 0x0375, 0xfd121200 / 7
USB Device: USB2.0 Hub, 0x05e3  (Genesys Logic, Inc.), 0x0608, 0xfd121400 / 6
USB Device: P'9231 Desktop Drive, 0x059f  (LaCie), 0x1059, 0xfd121440 / 10
USB Device: P'9231 Desktop Drive, 0x059f  (LaCie), 0x1059, 0xfd121430 / 9
USB Device: hub_device, apple_vendor_id, 0x9131, 0xfd121420 / 8
USB Device: Gaming Mouse G400, 0x046d  (Logitech Inc.), 0xc245, 0xfd121421 / 13
USB Device: USB Receiver, 0x046d  (Logitech Inc.), 0xc52b, 0xfd121423 / 12
USB Device: Apple Cinema HD Display, apple_vendor_id, 0x9223, 0xfd121422 / 11
USB Device: IR Receiver, apple_vendor_id, 0x8242, 0xfd110000 / 3
FireWire Device: Extreme IV FireWire Reader/Writer, SanDisk, 800mbit_speed

Answer 1

First, you need to realize that ASC is not an Apple tech support portal. It's a discussion site, to which anyone can contribute. As a result, you will sometimes get responses that are unhelpful. For example, if you ask a question related to kernel panics, you may get answers from people who like to give advice, but don't know what a kernel panic is or what can cause it. Keep that in mind.
1. This comment applies to malicious software ("malware") that's installed unwittingly by the victim of a network attack. It does not apply to software, such as keystroke loggers, that may be installed deliberately by an intruder who has hands-on access to the victim's computer. That threat is in a different category, and there's no easy way to defend against it. If you have reason to suspect that you're the target of such an attack, you need expert help.
2. All versions of OS X since 10.6.7 have been able to detect known Mac malware in downloaded files, and to block insecure web plugins. This feature is transparent to the user, but internally Apple calls it "XProtect." The malware recognition database is automatically checked for updates once a day; however, you shouldn't rely on it, because the attackers are always at least a day ahead of the defenders.
The following caveats apply to XProtect:
It can be bypassed by some third-party networking software, such as BitTorrent clients and Java applets (see below.)
It only applies to software downloaded from the network. Software installed from a CD or other media is not checked.
3. Starting with OS X 10.7.5, there has been another layer of built-in malware protection, designated "Gatekeeper" by Apple. By default, applications and Installer packages downloaded from the network will only run if they're digitally signed by a developer with a certificate issued by Apple. Software certified in this way hasn't actually been tested by Apple (unless it comes from the Mac App Store), but you can be reasonably sure that it hasn't been modified by anyone other than the developer. His identity is known to Apple, so he could be held legally responsible if he distributed malware. For most practical purposes, applications recognized by Gatekeeper as signed can be considered safe.
Gatekeeper doesn't depend on a database of known malware. It has, however, the same limitations as XProtect, and in addition the following:
It can easily be disabled or overridden by the user.
A malware attacker could get control of a code-signing certificate under false pretenses, or could find some other way to evade Apple's controls.         
4. Beyond XProtect and Gatekeeper, there’s no benefit, in most cases, from any other automated protection against malware. The first and best line of defense is always your own intelligence. All known malware circulating on the Internet that affects a fully-updated installation of OS X 10.6 or later takes the form of so-called "trojan horses," which can only have an effect if the victim is duped into running them. The threat therefore amounts to a battle of wits between you and the malware attacker. If you're smarter than he thinks you are, you'll win.
That means, in practice, that you never use software that comes from an untrustworthy source. How do you know whether a source is trustworthy?
Any website that prompts you to install a “codec,” “plug-in,” "player," "extractor," or “certificate” that comes from that same site, or an unknown one, is untrustworthy.
A web operator who tells you that you have a “virus,” or that anything else is wrong with your computer, or that you have won a prize in a contest you never entered, is trying to commit a crime with you as the victim. (Some reputable websites did legitimately warn visitors who were infected with the "DNSChanger" malware. That exception to this rule no longer applies.)
Pirated copies or "cracks" of commercial software, no matter where they come from, are unsafe.
Software of any kind downloaded from a BitTorrent or from a Usenet binary newsgroup is unsafe.
Software with a corporate brand, such as Adobe Flash Player, must be downloaded directly from the developer’s website. If it comes from any other source, it's unsafe.
5. Java on the Web (not to be confused with JavaScript, to which it's not related, despite the similarity of the names) is a weak point in the security of any system. Java is, among other things, a platform for running complex applications in a web page, on the client. That was never a good idea, and Java's developers have had a lot of trouble implementing it without also creating a portal for malware to enter. Past Java exploits are the closest thing there has ever been to a Windows-style "virus" affecting OS X. Merely loading a page with malicious Java content could be harmful. Fortunately, Java on the Web is mostly extinct. Only a few outmoded sites still use it. Try to hasten the process of extinction by avoiding those sites, if you have a choice.
Java is not included in OS X 10.7 and later. Discrete Java installers are distributed by Apple and by Oracle (the developer of Java.) Don't use either one unless you need it. Most people don't. If Java is installed, disable it — not JavaScript — in your browsers. In Safari, this is done by unchecking the box marked Enable Java in the Security tab of the preferences dialog.
Regardless of version, experience has shown that Java on the Web can't be trusted. If you must use a Java applet for a specific task, enable Java only when needed for the task and disable it immediately when done. Close all other browser windows and tabs, and don't visit any other sites while Java is active. Never enable Java on a public web page that carries third-party advertising. Use it only on well-known, password-protected, secure websites without ads. In Safari 6 or later, you'll see a lock icon in the address bar with the abbreviation "https" when visiting a secure site.
Follow these guidelines, and you’ll be practically as safe from malware as you can be.
6. Never install any commercial "anti-virus" or "Internet security" products for the Mac, as they all do more harm than good, if they do any good at all. If you need to be able to detect Windows malware in your files, use the free software ClamXav — nothing else.
Why shouldn't you use commercial "anti-virus" products?
Their design is predicated on the nonexistent threat that malware may be injected at any time, anywhere in the file system. Malware is downloaded from the network; it doesn't materialize from nowhere.
In order to meet that nonexistent threat, the software modifies or duplicates low-level functions of the operating system, which is a waste of resources and a common cause of instability, bugs, and poor performance.
By modifying the operating system, the software itself may create weaknesses that could be exploited by malware attackers.
7. ClamXav doesn't have these drawbacks. That doesn't mean it's entirely safe. It may report email messages that have "phishing" links in the body, or Windows malware in attachments, as infected files, and offer to delete or move them. Doing so will corrupt the Mail database. The messages should be deleted from within the Mail application.
ClamXav is not needed, and should not be relied upon, for protection against OS X malware. It's useful only for detecting Windows malware. Windows malware can't harm you directly (unless, of course, you use Windows.) Just don't pass it on to anyone else.
A Windows malware attachment in email is usually easy to recognize. The file name will often be targeted at people who aren't very bright; for example:
♥♥♥♥♥♥♥♥♥♥♥♥♥♥!!!!!!!H0TBABEZ4U!!!!!!!.AVI♥♥♥♥♥♥♥♥♥♥♥♥♥♥.exe
ClamXav may be able to tell you which particular virus or trojan it is, but do you care? In practice, there's seldom a reason to use ClamXav unless a network administrator requires you to run an anti-virus application.
8. The greatest harm done by anti-virus software, in my opinion, is in its effect on human behavior. It does little or nothing to protect people from emerging threats, but they get a false sense of security from it, and then they may behave in ways that expose them to higher risk. Nothing can lessen the need for safe computing practices.
9. It seems to be a common belief that the built-in Application Firewall acts as a barrier to infection, or prevents malware from functioning. It does neither. It blocks inbound connections to certain network services you're running, such as file sharing. It's disabled by default and you should leave it that way if you're behind a router on a private home or office network. Activate it only when you're on an untrusted network, for instance a public Wi-Fi hotspot, where you don't want to provide services. Disable any services you don't use in the Sharing preference pane. All are disabled by default.