Standby Issue

Hello all!

I am having a strange problem with standby on my PC. To begin with, here are the specs:
Emachines W3506 Desktop
Intel Celeron D 3.4GHz 533FSB
Intel D101GGC2 MB
512MB DDR2 PC3200
XP Home SP2

The system used to work just fine, but here recently it has stopped going into standby. Whether I manually force the system into standby or the system is set to after x minutes, it seems to take all the right steps, but the system doesn’t actually power down.

The monitor goes into power-saving mode as it should, and the power button light turns off on the tower, but the CPU fan remains running, and the status light on my combo USB/Card reader remains on, so the system isn’t standing by. What could cause this? I’ve already checked all settings in the Power Management and updated/checked the MB BIOS. Any ideas?

When I cause an interrupt, i.e. a key stroke or mouse movement, the monitor comes back on and all is back to normal. Because I’m using a CRT, i can’t tell if the display is the only thing standing by or if it all is, because even when all worked perfectly the system would resume before my monitor would power back up.

Any help on this matter would be GREATLY appreciated!