I have an Optiplex GX620 that randomly goes into to standby mode while it is
in use. I had a user that was working constantly in Excel and suddenly, the
monitor went blank and the computer appeared to enter standby mode.

I have tested several possibilities including remote access to the machine
during these sleep periods. This was unsuccessful as the machine drops off
the network as if it were turned off.

The power button on an Optiplex should blink in standby mode and it does
not. I have disconnected the monitor from the onboard VGA output to an AGP
DVi connection with no success.

I have been unable to bring the computer up out of standby without
completely rebooting the machine.

The problem is definetely not related to the computer not being used as I
myself sat down and began troubleshooting...almost as if on cue, it went into
standby. This is the second computer to do this in the last week. I'm
unusure whether this is a hardware issue or related to Windows. The OS is
WXP with SP2. This computer is on an enterprise WAN and other computers
don't seem to be having this problem.

Any help would be appreciated.