I've heard of this before...but never had it. Copy them to your computer before you do this so they aren't lost...and then see if your gopro is up to date software wise...maybe something is going on that an update will fix.
I have the same problem. I can only watch my videos on the tv. My computers arent fast enough to process the info. Try to record in a lower resolution to be able to play back and edit. Lots of people I know use a mac book pro. Kinda expensive for the casual video guy, but the serious ones love them