All my video issues resizing the screen causing MP to resize to half the window, are now gone with an updated NVidia driver for my video card.
I'm not sure if that solves your problem, but it is an easy one to try. I'm now able to turn on and off my TV as I like, with MP always exactly where I left it.
Well, this is very good news! I have ATI, but this means that the problem is on the driver side and CAN be easily fixed. Will try to update my ATI drivers and see if this helps. Can you look at the changelog of the Nvidia driver and see what might be fixed or added that probably solved the problem?
EDIT: upgraded to the newest ATI drivers, the problem still remains. How irritating is this, I just can't believe this could not be fixed?
Jadz: did the nvidia driver upgrade fix your problem completely?