Problems w/ 360

I recently bought a used 360 and it works fine except during the cutscenes in games. During Gears of War during any cutscene the audio rolls along perfectly, but the video does not catch up and lags behind often freezing. This isn't a problem w/ regular xbox games only 360 titles. Also when playing 360 games my system seems obnoxiously loud. Does any one know what could be causing these problems?