ok so im trying to make a movie, and i have several videos that i uploaded onto my computer from my iphone that im using. so far, the first two videos play clearly on my movie, but the one im trying to do next keeps freezing in the middle of the video, yet the sound still plays. its so stupid and frustrating! and i even deleted that third vid, and pulled it back up to movie maker again to see if that would make a difference, but it still freezes. help???!?!?!!?!?1