I’m having the same problem too. Using Windows 7 32 bit and Sony Vegas 10. Was working fine for 1 week until after a render Sony Vegas started saying Quicktime wasn’t installed & subsequently won’t accept MOV files. Closed down Vegas, restarted the computer and tried opening any MOV with the Quicktime player but the stand alone player won’t run as well. Have uninstalled and reinstalled Quicktime multiple times with no success of getting the Quicktime player to work, let alone Vegas. H-E-L-P!!!!