screensaver & monitor shutdown not working

I put Vista HP-64-SP1 on this machine about six months ago. In Power
Options, there are settings for display (monitor) shutdown and sleep
shutdown. The screensaver and monitor shutdown settings worked fine for
about 3 months. Then Vista would not shut down the display; so the monitor
stayed on until the 'sleep' setting came into play. Today, the house 120v
power went off. After resetting the surge protector and numerous reboots,
Vista now will not run any screensavers (and it still won't shutdown the
monitor). I've reset the SS and shutdown settings a zillion times, including
the defaults, and nothing will make Vista perform the shutdowns. Which means
I can't leave the computer inactive for long periods, otherwise I'll burn the
monitor screen. I assume some Registry settings are screwed up?
--
Thx, Doug