Windows 7: No DVD audio in WM7, but WMP12 is OK

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.

So I installed the trial version of PowerDVD and it solved the problem. Go figure, lol.

I spoke too soon. PDVD had no effect.

But ... I discovered something. When I opened a media file (DVR-MS or TS) directly from Explorer, the file would play. If I opened it from WMC's library, it would choke and I'd get the video error. The only thing different was, if I opened from Explorer, there was no sound when WMC opened. I noticed that navigation sounds in WMC are PCM, and the problem seemed to be it couldn't switch from that to bitstreaming the DD/DTS track on the files. So I turned off sounds, and whaddya know -- problem solved!

Can anyone help me understand if this is a Win 7 issue or maybe one with my video card?