This is a REALLY strange problem, and I'm wondernig if you guys can help me with it.

My PC is goofed up. The problem only happens in Windows 98 (I'm running Linux now), and it seems to happen at random. After a little while (sometimes hours or days, sometimes minutes) the screen will go blank (the green monitor indicator light goes from green to yellow, which means "no signal") and I can't Ctrl + Alt + Delete, can't use the reset button (works fine otherwise), nothing. However, I can power it off by holding the power button for 4 seconds (hard power down).