I've been having an odd problem intermittently every several weeks with my Windows 7 PC. If I put it to sleep, occasionally, when I try to wake it up, the monitor will receive no signal.
It seems that it is not waking properly because when it does, the fans spin up to full speed briefly but then return to a quiet idle. In these cases, the fans will continue on full blast indefinitely until the machine is powered off. If the machine is booted up again after this, it will display the same behavior every time it boots. If a key is pressed on the keyboard, the Num Lock light will flash briefly.
The only way to solve this problem has been to unplug the power cable from the PC for a few seconds and then start it back up. Then, it just boots as if it were waking from sleep! (Displays "Resuming Windows" and starts up with all my previously open programs running.)
I can't figure out what's causing this, but I figure it must be a hardware problem with the PC, because I've tried swapping video inputs, powering the monitor on and off at various points before, during, and after booting, and unplugging the PC is consistently the only thing that fixes it. Might have something to do with long uptimes because this seems to occur after a long time without restarting.
Acer Aspire ASE700-UQ660A (Specs should be all factory defaults except:)
4 GB RAM
Nvidia GeForce 8600 GT with driver version 197.45
Windows 7 Professional 64 bit