I have a Windows XP system that always forgets to turn of the monitor.
In Display Properties/ Screen Saver/ Power/ Power Schemes I set "Turn off monitor" to any value from the pull-down list (lets say 5 mins). Click OK twice. Five minutes later, the monitors will blank exactly as desired, and come back on with a key press or a mouse movement. This will continue to work an indeterminate number of times.
But sometime that same day it will stop working, and the monitors will remain on. It never starts working again by itself. If I return to the Power Scheme the monitor box is still set as above (it remembers the setting, even though not working.) If I change the setting, say to 10 mins. and click OK, then it will start working again -- for a while.
So Windows is not forgetting my power settings -- it is forgetting to apply them. What service or driver has that task? Anybody seen this problem & fixed it?