Quicktime or Windows Media Player crashes explorer

I have both programs on my computer, and up until this week, they've always run smoothly together. Don't know what happened or why, but now everytime I single click or double click a mov file to open with quicktime, the MPlayer (default and to the left) tries to play it (???) and though the movie does go ahead and open in QT player, the windows explorer crashes (not internet explorer - windows explorer). It does not crash if I manage to quickly click the stop button ont the little media player default before it starts trying to play it. So I am assuming the crash happens because the wmp is trying to play the mov file? I've reset both programs to open the appropriate file extensions, but nothing helped.

I've uninstalled and reinstalled both programs repeatedly, with no sucess. Please help...almost all of the family movies taken with our camera are quicktime movies...and we do watch them a lot.