Volume for movies really low

My XBox360 works great except for when I try to play DVD movies.

It seems like the sound is REALLY low and turning up the volume on the tv to the max does not work. Games play at the correct volume, but everytime I play movies it's really hard to hear.

Im playing on an HDTV if that makes any difference.

Thanks!

It must be a problem with some movies that have 5.1 audio when you play them on stereo. Happens to me as well, actually both on the 360 with HD-DVD and on the PS3 with Blu-ray.

Older DVD's that have a stereo audio track don't give me this problem.