I went on vacation and came back four days later to find that my computer would not start. Pressing on the power button did not do anything...it was simply dead (no spinning fans, HD, etc.). At first I thought that maybe my PSU or some other component got fried because we had a brief power outage/brownout the day I left for vacation (the computer was running at the time). However, it was hooked up to a UPS and to my knowledge the computer never lost power/shut down unsafely (I was able to use and shut it down normally after the brownout). Also, when I opened the case I saw that the motherboard LED was lit just fine whenever the computer was plugged in...so at least I knew that the PSU was providing power. I checked the power button cable/connectors and also found nothing wrong. After some further experimentation, I discovered the (temporary) solution: I must take out the CMOS battery and leave it out in order to be able to start the computer. Otherwise, it simply refuses to start. I find this very strange since CMOS battery problems usually lead to loss of BIOS and time settings but never have I read a case where the battery itself was preventing the computer from starting up. So right now the computer is running fine...just as long as I leave the CMOS battery out. I have found no other issues so I doubt that anything (except maybe the CMOS battery) got fried during the brownout. Obviously, I lose my BIOS and time settings everytime I kill the power or unplug the PC and have to re-enter those everytime I restart...but as long as I keep it plugged in, even with the computer itself shut down, the BIOS settings do not get lost/reset. So thankfully this is still a minor convenience, for now. Has anyone ever heard of a case like mine? Is this a simple dead CMOS battery issue? Can a PC refuse to start with a dead battery sitting in the slot? Or could the battery be causing some kind of a short and therefore prevent the PC from starting up? FYI, I assembled it myself in late 2002. It's old, but not that old (I have two 8-year-old Dells whose CMOS batteries are still running fine). I have not had time to get a new CMOS battery, but this was going to be my next step. Do you think this will resolve the issue? If so, should I get a battery at maybe Radioshack or should I not bother and just order online? Sorry for the verbose post. Thanks in advance!