OK. I've got a tough one (for me, at least)... I have an iBook G4 running 10.5. It's a 12" Late '04 model with the 1.2ghz processor and it has a stick of 512MB RAM, bringing its grand total to 768MB. In addition, it has 32MB of VRAM as part of the integrated graphics built into the logic board. The problem: The computer will run fine for a couple of minutes. It will boot up OK, let me login and let me onto the desktop. Eventually, after a couple of minutes, it will suddenly freeze. The beachball will come up and then it'll go away and the entire computer will be frozen. I can't move the mouse, I can't type on the keyboard -- everything is frozen. The only way out of it is to reboot the machine. What I Tried: I tried booting into safe mode, to no avail. I tried checking the logs and seeing what's going on in verbose bootup. It worked for a while in single-user mode so I thought it might a software issue with the OS installation. I decided that I was going to reinstall the OS again anyway, so I wiped the hard drive and reinstalled Mac OS (Leopard). Now, however, I can't get past the registration info on the setup assistant. I get to watch the opening video of the installation play (because it was successfully installed on the hard drive) and when I get to the textboxes to enter my info, the computer has the same freeze problem. I wanted to completely rule out software, so I tried booting up from a Live CD of Ubuntu. This did not work also. I ended up hanging on initialization of the graphics. I tried taking out the stick of RAM and running the Live CD, but the same problem occurred. I usually know what I'm doing when it comes to troubleshooting computers and fixing problems, but I'm honestly stumped. Does anyone have ANY ideas?