This problem first happened with RC1 of Vista. I’d press the sleep button (or select Sleep from the Start menu). My PC would go through all its shutdown things, blank the screen and immediately wake up. After a short while the login screen would be displayed, I’d type my password and be back where I started.

I read on the www.tabletquestions.com forum of other people who’d had similar problems and some had referred to a POWERCFG utility. This turned out to the problem on my PC.

I ran this utility (in a Command window, as administrator) with the “–DEVICEQUERY wake-armed” parameters and got a list of hardware devices that would wake the PC up. This showed:

C:\Windows\system32>powercfg -devicequery wake_armed
Standard 101/102-Key or Microsoft Natural PS/2 Keyboard
Microsoft USB Wheel Mouse Optical

So if there was activity on my mouse or keyboard, the system would wake up from sleep. It seems that when going to sleep, there’s enough activity from the mouse to wake the system up. Also I didn’t really want the PC to wake up just because I’d moved the mouse out of the way on my desk. So I disabled the mouse as a wake-up device:

C:\Windows\system32>powercfg -devicedisablewake “Microsoft USB Wheel Mouse Optical”

Now the devicequery request does not show the mouse:

C:\Windows\system32>powercfg -devicequery wake_armed
Standard 101/102-Key or Microsoft Natural PS/2 Keyboard

It could be argued I don’t want the keyboard to wake the PC up either, but my motherboard does support wake from sleep on the keyboard so I might give that a go in the future – at the moment it’s disabled in the BIOS.

Anyway my PC now goes to sleep.

Why write about this now, since the problem happened with RC1 and did not resurface when I installed a full version of Vista. Until yesterday when I replaced the power supply and case. It’s possible that changing the PSU caused Vista to lose its power settings.