Maybe if you provided a little more information someone would be able to better assist you.
XBMC build? (Usually if you are running an old build the advice is to upgrade and try again)
Copy how? (DVD, CD, FTP, etc.)
What type of movie? (AVI, DVD, etc.)
How large of movie? (700MB, 4GB, etc.)
How far does it get before failing?
You might want to try debug logging to see where/why the transfer fails.http://forums.xbox-scene.com/index.php?showtopic=448473