I have the exact same problem with this card.
I had win 7 32bit since the pc was delivered to me with this problem.
I have searched every methods they say in other forums about that but yes i havent found anything. On my personal reasearch i have found out that the pc plays the videos with no problems on safe mode, and also when i disable the drivers of the graphics card.
So i am pretty sure that its a driver problem, but i cant find any older versions on asus site. if anyone finds something please post it here.