Imac stops-sleeps unexpectedly

Question

My G5 iMac goes to sleep unexpectedly, usually in the middle of something I don't want to interrupt. It does it
-when I burn audio CDs from iTunes (hour long mp3s)
-when I record audio input from an LP (but not when I record streaming audio from RealPlayer)
-on some heavy web pages (Disney stuff, w/ a lot of flash & audio).
Each time, it just dies - clicking brings it back as if it was coming out of sleep, but it interrupts whatever was happening previously.
Thanks for help!

Answer 1

A number of sleep-related issues can appear after incremental Mac OSX updates, including the inability to properly go to sleep, problems waking from sleep, and having your display go to sleep without your Mac going to sleep. The most common culprit is Bluetooth. Try these tips to fix your sleep problems.
WAKE UP
In System Preferences>Bluetooth, uncheck Allow Bluetooth Devices To Wake This Computer. If you are using a Bluetooth mouse and keyboard, you'll have to wake your Mac by pressing the power button.
FILE CORRUPTION
Your Bluetooth preference file may be corrupt-you'll need to delete it. Turn Bluetooth off, then go to the /Users/user name/Library/Preferences folder. Look for a file called com.apple.Bluetooth.plist and trash it.The OS will create a new preference file when you enable Bluetooth again.
ENERGY SAVER
If you have issues with a Mac or display that goes to sleep at inappropriate times, you may have a problem with Energy Saver. Delete the following .plist files and restart:
-/Library/Preferences/SystemConfiguration/com.apple.PowerManagement.plist
-/Users/username/Library/Preferences/com.apple.systemuiserver.plist--(username is your name or System Administrators name).
-/Library/Preferences/SystemConfiguration/com.apple.AutoWake.plist
A restart is very important after deleting these plists. After a reboot your Mac will then generate new ones.
In some cases, running MacOS X's cron tasks-maintenance that the OS performs automatically if you leave your Mac on 24 hours a day-can resolve many sleep problems. If you don't want to leave your Mac on, you can use MacJanitor, Yasu, or OnyX free at Versiontracker.com.
Cheers!
DALE