My wife has a very strange problem with her Windows 7 desktop: the screen will switch itself off after a while, which is expected and wanted, but it the immediately switches itself on again. Can this be caused by a program she has installed? And is there a way to easily figure out which one?
Are there any vibrations where the mouse is sitting?
Try going to power saver settings and unclicking the check box for "Let this device bring the computer out of sleep mode".
It says something like that anyway.
Try changing the setting for when the monitor goes off to a different setting and see if that helps.