Vista black screen from sleep

OK, I've spent an hour on the search engines, but no luck yet. I accidentally told Vista Business 64 to 'sleep' instead of 'power down'. Now when I try to reboot, only fans run and the CD drive LED blinks a few times: no BIOS, no USB keyboard LEDs/response, no USB mouse LED/response, nothing on the monitors, not even an LED on the power button. I've also tried swapping the positions of the 2 RAM sticks, unplugging the HDs, putting in the Vista DVD on boot, leaving it physically disconnected from the wall for >5 mins - nothing.

HW is Asus P5Q SE mobo, MSI Radeon R4670 graphics, 4GB RAM. As far as I know (I can't get anything out of the computer now), drivers and BIOS were reasonably up-to-date, had no problems for the past month.

Any clues? I need to do some work on that computer, I'm on a co-worker's computer right now!

Thanks!

Thanks - resetting the CMOS jumper is what finally restored the system. I'll have to check at the Asus site for an updated driver.