This problem just happened to me recently and i am not sure what i did that triggered it, it never happened before. The "allow screen saver during playback" option in WMP is unchecked. My laptop power management is set to "balanced". Can someone please help me out? I'd rather not have to turn off my screen saver every time just to watch movies or videos.
Windows Vista Home Premium 64-bit 4GB RAM Intel Duo Core 2.5Ghz