I agree with PinkSpider- these things are usually due to encoding problems (gpcinema is very picky). Also, if your using windows xp you may want to try gpdrive to transfer your files to the gp- its just faster, especially for movies and such (just remember to press select when the file transfers over). If you feel its not due to endoding problems, try downloading something specifically encoded for gp (Sam Fishers torrent site has some and theres another site that has a few vids as well). Also, make sure your running gpcinema at at least 133. Hope all this shit helps