When ever I try to play a tv show it doesn't work?

Whenever i try to play a purchased tv show from Itunes a single image appears and sound plays for a couple seconds and then it just doesn't work. These videos used to work and I haven't installed any new graphics drivers or anything. Wherever you go in the video this happens i can go to a random part and it will be frozen but audio playing for about 3-4 seconds. If it matters my specs are:

I5 3770k processor

AMD radeon 7950 graphics card

650 watts of power

blah blah you don't need to know the rest

It would be great if someone could help with my problem, thanks