iMac G5 PowerPC keeps shutting down, no reason!

I have a 5 year old iMac G5 (PowerPC). I have owned it since new. I own the white 20" model, with no iSight on the front. I have had the HD replaced due to a spill the iMac took a few years ago. Other than that, it has been good to me until now.

The iMac shuts down on me a few times a week. Everything is going fine and then, out of the blue, the opaque gray screen starts scrolling downwards and the opaque black box appears and says that it must shut down. I have restored the iMac to it's original factory settings, in hopes this would cure the problem. Everything was fine for a few days after the restore, then it happened again. Since that first episode after the restore, it continues to do it 2-3 times per week.

Any help? Has this happened to any of you? I look forward too your help and input.

Kindest regards,
Nuts4Mac

What you're experiencing is known as a kernel panic. KPs happen for a variety of reasons, but many times they're related to faulty hardware.

Anything change recently hardware-wise? Any new memory, for example?

And you can also try Apple Hardware Test from disc one of the original install discs, and boot from the install DVD and run Repair Disk from Disk Utility there and see what is reported.