Windows XP Power/Turn Monitor Off

I set my monitor to turn off on my laptop after one hour, but it doesn’t work all the time, only sometimes, anyone have the same problem or know how to resolve this, is this a glitch that’s fixable?

I found out if I fell asleep watching a movie in Windows media player none of the power saving tools worke .

Some running programs over ride that setting. I know WinTV 2000 (my TV card software) does. So does WinAmp when I’m running certain visualizations.