Vista - Vista Media - TV + DVD video but no sound.

Hi All!

Have a strange Vista problem. Sound works in all places apart from
Media Centre mode. Volumes have been checked and they are all UP.
I have got the decoder checker and there are entries in both Video
decoder and Audio decoder. There are no other codecs I can select but
the sound is still missing. I wonder if someone can tell me what is
the name of the Audio codec they have listed in that section, so that
I can compare and if necessary reload it.

Thanks