Windows Movie Maker Problems

SO I’m trying to edit a video but I’m having a real hard time seeing what’s going on. Now, I know WMM sucks but it’s all I have so it’ll have to do. My problem is that every so often in the time line the video will freeze and skip making it really akward to edit it properly. If I save the video it doesn’t happen so the final results are fine, it’s just getting really annoying. Is there any way I can aviod this? Or better, why the hell is this happening?