If you machine freaks out at really random points then I would recommend testing it’s memory. The “Techtools deluxe” you find on the CD with the red edge you got from Apple appears to be pointless. Duing 15 minutes of beachballing I was able to click on 3 different messages, but it never worked. At least on the G5 that was broken today it was a complete waste of time.
I downloaded this very very nice memory tester
it it worked right away. Found the bad memory and that was that.
Here a little how to:
1. Install the program
2. Reboot your mac and hold command/apple S while the machine is coming up
3. You will be in the text based single user mode. Don’t be scared
4. type /Applications/memtest/memtest
(tip: hit tab or ESC twice to auto complete the command)
5. see what the test is saying: bad memory kicks out lots of error messages