WMV audio out of sync after fast forward

Hi

I am running Vista Home Premium edition. I can run WMV files fine in Media
Player (or Media Center), but if I fast forward or rewind then the audio will
be slightly out of sync with the picture.

I have checked the WMV files on another machine (XP) and they work fine (the
WMV files are mostly downloaded from BBC iPlayer website, so I doubt there is
anything wrong with them).

Opening the file in graphedit gives the usual windows filters (quart.dll
into the 2 WMVideo / Audio DMO Decoders, then into the video renderer and
directsound device) no other filters appear.

Strangely fast forwarding whilst previewing in graphedit does not shift the
audio out of sync.

the PC is a intel core2duo with 2 gig of RAM, and runs HD material fine.

Anyone any suggestions?

Thanks
Ricko