I want to watch my movies from i tunes on my mac book pro but can't !

I recently purchased a series from iTunes, i can play it on the main computer but can't play it on my lap top. Music is fine, but not tv , i changed playback to 720, it played a couple of seconds and that's it., it's just frozen. blank screen or frozen images. pfft. it says if it was a network problem i would assume i could play the series on the main computer. also turned on and off my router , any suggestions, nothing too complicated., a little computer illiterate unfortunately. cheers rose.