I believe that MS, in one of their upgrades, deleted the DVD codecs out of WMP, i.e. you could play DVDs on V8.0 and V9.0 but not V10.0 onwards.

Try a different media player, such as VLC http://www.videolan.org/vlc/



UK Bob

PS. Although I have WMP V10.0 and I can play DVDs, I had to install several non-MS codec packs to put back what MS had deleted. If VLC doesn't work I will post a list of the codec packs I installed after I get home tonight.