How large are the files?
What are the movie files extension(s)?

Normally if VLC cannot play it (make sure you have latest version), then I'd suggest something is wrong with the file itself.

Is there any more detail on the error VLC gives?
Are you actually able to open the file with VLC (but not play it)? If yes, control i keys to get information, Codec tab, and open the stream tabs & see what it says for each of audio & video streams for kind of data.