Screensaver has ceased to function

Not sure what is happening. I have a new HP puter (Vista64) and initially the screensaver worked fine. Now it has stopped. I checked and it is still set to activate in 10 minutes. I figured there may be a program running in the background that's saying the puter is being actively used. Used msconfig I disabled several nonessential items, but the screensaver refuses to function. Strange. I'm new to Vista, so perhaps there is something I have missed. Any help would be much appreciated.

Thanks,
Hank

I'm OK now. I forgot that I installed a MS wireless mouse and keyboard. Had the same problem a couple of years ago with XP. Installed the HID update and the screensaver is fine.

Hank