have a Power Mac G5 Dual 2 GHz 1 GB DDR OS X 10.4.11 I haven't made any recent hardware changes, i've tried doing a clean install and using a new hard drive. The computer keeps freezing at random times. I will be able to move the mouse but the rainbow circle will keep spinning and I am unable to click on anything. I will have to hold down the power button to shut down. Sometimes when it freezes like this I will hear the fans spinning very fast and loud. It is strange how sometimes it will last a few days without freezing and sometimes It won't last 5 minutes without freezing. I also find, many times if i turn the computer on and just leave it....it will not freeze, but then after i use it for 10-20 minutes, it will freeze. Currently I only have a fresh installation of OS X Tiger installed. I have ran Disk Utility, Apple Hardware Test, Apple Jack, TechTool Pro 4 and no errors have been reported. Since this problem has began, I have now installed a new logic board, 2 new processors, new hard drive, new memory and the problem is still ongoing. Any suggestions on what my next step should be to resolve this issue???