I'm running Win 7/64 Home Premium with an nVidia GT-430 (301.42) connected via HDMI to a Denon 2310CI.
I don't normally use Media Center to play DVDs, so I have no idea when this issue started, but when I try to play one, the video will play for a few seconds, but there is no audio output. Then I get the dreaded "Files that are necessary for playback are not found ..." error, which, of course, tells me next to nothing. I encountered this same problem with Vista (which is one of the reasons why I upgraded to Win 7/64).
Thinking it might be a conflict with 3rd party codecs (since uninstalling ffdshow in Vista cured that for a while ... I think, I can't really remember now ...), I uninstalled ffdshow, LAV filters, Haali spliter and rebooted. Didn't help. Meanwhile, DVDs play fine in WMP12. Also DVR-MS and TS files will bitstream AC3/DTS fine when played in Media Center.
Looks as if something is broken, but I don't know how to proceed. Does anyone have any ideas or some solid links that could help out? The problem isn't worth re-installing Windows, but I'd like to be able to fix it just the same. Thanks.