Windows 7 wake from sleep problem

For the past few days on I've been experiencing an odd problem on my main Windows 7 (64 bit) box in that the machine doesn't reliably wake from sleep. (Specifically, the hard drives/fans, etc. sound like they're spinning up fine, but no video output occurs and the system just sits there whirring away.)

If I power off by holding down the power button for three seconds and then start up again, the machine then goes into resume mode and eventually all is well. I've tried disabling hybrid mode and running "powercfg.exe -h on" as per this existing question/answer, but this didn't make any difference.

The machine has been fine for 6+ months, I've installed no hardware, software or made any configuration changes and there have been no software updates since the 13th (nearly two weeks ago).

As such, I'm stumped. Any suggestions?

It transpired that this was a hardware issue.

I recently had to replace the power supply, as it was failing to start the machine despite there being some power to the motherboard. (It was making a faint whining noise, which I'm guessing was a capacitor on the way out.)

Since replacing the power supply, the machine now sleeps normally.

There are a couple things that you could try. The first thing is to do a system restore and see if this problem still occurs. The other thing is to reset your power management settings back to default, restart, then change them to your preference. These are very basic suggestions, but hopefully they'll pan out.