Okay well, I've done everything I can think of and I haven't got this problem fixed, so...
My computer has this problem (which I strongly suspect is the bios), and it works sort of like this: You try and turn it on, but half the time you won't hear it beep (some kind of signal from the bios, I believe) and the screen light remains amber, which means you can't see what's going on.
On more rare occasions, it will beep, the screen will turn on, and it'll begin to run through the startup sequence. Sometimes it manages to get into windows, sometimes it doesn't make it any farther than the startup screen. But at some point the computer always completely locks up, blocking out all input. I'm not sure if this is because it is ignoring mouse/keyboard input or some other reason.
Also, after I got into windows once or twice, it mysteriously did something that disabled my ATI driver, so now my Radeon fails to work.
I have reset the CMOS jumper on my motherboard, checked all wires/connections, and reset the processor.
Stats (I list everything, since I don't know what's wrong with it):
Motherboard: Abit AS8
Processor: Pentium 4 w/HT
Graphics Card: Radeon 9800 Pro
CD drives: Taken off a Dell 2350
Hard Drive: Also taken off a Dell 2350
RAM: 1 GB
Ideas?