Closed Unassigned: MP4 plays in WMP, but not in WMC [1750]

The program is working perfectly to convert WTV files in Win 7 Ultimate to MP4, but the files won't play in MCE. The frustrating part here is that the problem is not consistent. All videos will play on Windows Media Player or VLC, but on Windows Media Center I get a blank screen on all videos except 2.

I have installed various codecs, including the FFDShow, but the problem persists.

Thoughts?