Windows Media Center

This is one of those annoying little problems. I have a multiple monitor
set-up. Occasionally, I like to play movies or whatever on DVD in WMC on a
smaller monitor I have. The problem is that I can't minimize WMC to a
smaller screen so I can operate Vista *and* watch the movie at the same time
- all of my monitors go blank except my main monitor. At one time I was able
to but, for some reason that stopped. When I click the "middle botton" on
the upper right WMC disappears and I can't restore it just by clicking the
task-bar either.
So, how do I resize WMC so it is just a window instead of having it take
over all of my monitors?

Thanks.