I can't give you advices, but i can just say that i have the exact same problem... i'm trying to get answers but so far, not helpfull...just want to let you know that your not alone.
Just tell me something... is all ok when you try to open videos in your WMP?
IĞm asking that because in my case the same happens with other programs, specially audio and video an iĞm trying to figure out if the to problems are related.
Thanks.
Filipe