1080p Movie Playback Issues

Good morning,

I've been experiencing issues for a couple of weeks streaming a 1080p movie via iTunes that I purchased well over a year ago. When selecting to start/play the movie, either iTunes freezes/crashes, or nothing occurs, and the player fails to load. The movie did load once on a couple of occasions; one when I left the player alone to load for 15 minutes, and another when selecting a lower quality playback.

The 'iTunes Extras' part of the movie plays completely fine too .. Issue only appears to be with 1080p playback of the movie.

Any suggestions?

Thanks.