So I have a 2.0DP PowerMac. I have it for about 5 months and I bought it used off eBay. It was still on AppleCare when I got it, but it expired last week and I didn't extend the AppleCare. It hasn't missed a beat to date. This is what happened today. I put it too sleep this morning before going to work. I'm not sure if it fully went to sleep though. I push the button and the monitor shut off, but the machine kept running and I though it would go to sleep. Anyways, I left for work. I get home 10 hours later. I hear loud fan noises. WTF? I try to wake it. Nothing happens, just more fan noises. All of them must have been spinning at full RPM. The machine is frozen. I plug the power plug to kill it and then plug it back in. Turn is back on. No problems. I check the CPUs temperatures too make sure this thing didn't over heat and go into a safe mode/full cooling. Both CPUs were under 100*F. My heart finally slows down and that its. Everything seems to be cool again. But why did it do this? I do have a Belkin 5 port USB PCI card in the machine. No programs were running. I have my keyboard plugged in. USB I have my Microsoft Wireless Optical Mouse plugged in. USB Logitech USB mic plugged in. USB Epson CX4800 plugged in. USB iPod dock was in the firewire with no iPod docked. I haven't even tried putting it to sleep since I installed the Belkin USB card. I know some USB cards were know to kill the sleep on these machines. That's it. Too weird and scary. I don't want to lose my baby. Can anyone explain?