Hey, You bet, really annoying... I had this when playing DVD's a couple of years ago....almost ended up being thrown off the Deck!! As I recall, this was a software sync-ing problem (*read that as driver), but took me way too long to solve trying to get all drivers talking the same stuff to each other, at least at the same time.
Are you using MCE?? paparazi & I had similar problems recently with drops, delays, etc... mine was/is a cable signal issue. No problem with over the air signal but on the cable///bad...wound up piping cable through a VCR tuner and using that out to the PC/TV card. Not eletrical enough to know what this does but it worked. Something to do with the digital video signal and a quasi digital sound or something that I didn't understand.
Hope this gives you enough to experiment with. Find some results report back with what you determine
rvnguy
"I know everything..I just can't remember it all