Problems With Ac3 Sound using win 2000

[roiobr]

Hi, i have some movies in divx format in my home. And most of them are using the ac3 sound format. However when i try to watch them in my win2000 the sound have a lot of noisy and scrachts, like a high frequence... Only in the win98 i can see these movies with this specific format sound without problem. I have the ac3 codec installed in my computer, the newer version, but this is not fix the problem...

My sound card is a creative 16 bit, awe 32...

Does anyone here know what's going on??

Thanks, Léo