Screen Saver cannot work

[warrenw]

My os is Win7, recently the screensaver does not work, I have set the time to be 10 minutes but there is no screensaver after 10 minutes, how can I make it work ?

[Midknyte]

Sounds like there may be an application in the background that prevents the screensaver from coming on.

This is the app i use to turn off the monitor. You can manually shut off the screen with Monitores by locking the workstation. If the screen comes back on immediately, then you know something is interrupting it.
http://code.google.com/p/monitores/