Windows Movie Maker corrupting files!

So basically I spent an entire hour filming a video. It's actually quite important. I have tried to edit 4 times and EVERY time it corrupts it all. It's the second time I have filmed the video just to make sure there was nothing wrong with the actual video. I'm really mad and I thought it was because I was working too fast so I slowed down the fourth time I edited it and I got no warning and it just corrupted every sing file! this is ridiculous now and I've been searching for another editor with no such luck. Somebody please help as soon as possible this video is very important! Thank you