Video playback problem

I have a 5G 60GB ipod and recently ive been getting stuttering video and audio when i try to play a movie. Some of the movie files are rather large files for external playback, but it seems to happen with all sized files. If i reset my ipod by holding down the menu and select, the video plays okay. But if i listen to some music and then go back to video, the stuttering is back.

I just updated to ipod 1.1.2, but the problem is still there. Anyone come across this before? Its getting really annoying and i dont know how good it is for my ipod to keep resetting it.

Thanks in advance for any help you might provide