Somewhere I lost the ability to preview mpg's in other tools:
DVD2AVI blank preview
Womble blank preview in input window, works fine in output window
MS media player 9 blank video

I DID disable the MC codecs ala Sony's knowledge base article - still broken.

Vegas 5 works fine w/MPGs or VOBs
Power DVD plays mpg's and VOBs fine.

ideas on how to debug? thanks in advance