WMP11, Lock/Unlock Full Screen Mode

Ok, so here's how it's not working; I'm trying to watch a DVD on WMP11. I start playing it, and I click on the little paddlelock icon in the lower right hand corner of the frame. It "unlocks" with a window to put in my 4 digit code, and I do so, then I click on the green check mark, and the paddle lock closes, and then I proceed to watch my movie. Roughly 12 minutes later, (usually while I'm into a good scene in the movie), the screen switches from "Full Screen" view, to "Normal Screen" view, and stays that way until I complete the whole process all over again. This continues throughout the entire movie.

I've eliminated my screen saver as an issue, (this was suggested to me by someone), and have uninstalled Faststone Capture, (this was a screen capture tool that was constantly "on" in the background, that was also suggested as a cause), but I do still have another screen capture tool installed, however this one, Jing, does not constantly run. It is just an application I can start when I want to.

Anyways, this is my issue with WMP11. Oh, before I forget, I'm running Vista Ultimate, on a 32-bit system. It's all on a Dell XPS410 w/ an Nvidea GeForce 8600 GT video card. And all drivers have been updated. Any other questions will be answered ASAP. Thanks in advance.