videos studder on my player at 160x120
 

for some reason, every time i put a video on my fmp 1.8, at 120x160 or 160x120, i forgot, but anyways it makes studdering sounds every ten seconds, and it's REALLY annoying. it does it only on the player, and it's DEFINATELY not the head phones. on the computer, when i play the file, it doesnt have the studdering.
also, when i put it on 128 by 128 it doesnt make the sound. my converting tool is amv transform aka amv converter 4 mod.
this happens to videos in avi, and in mpeg, and every file. there are only 2 out of 10 videos that i converted, only make the sound 2 times. (at 120 by 160)
what can i do to get rid of the sound?