Hmm, i not sure whether this is correct alternative or not ...
Sometime if the file can't open, pls move it to ur desktop and try open it again.

Example, if my movie saved in an external drive, it just seem wun work with any player, but once i removed it to desktop (main page), then it works without any fixing.

Dunno how to explain this case, but u may hv a try.
Good luck