i have the exact same problem!Edit: Most movies also almost stop at the very beginning of playing for a few seconds.
at the beginning of a movie the first few seconds the movie stops/stutters (sound is working), and then after a few seconds, it runs normally.
with older build of xbmc i didnt have the problem.
movies are playing from a synology nas server, so it's just an .avi file.
i think it's 3.5 related
any ideas?