windows vista movie maker keeps crashing my pc?

whenever I try to do on Movie Maker I can edit files, then bam I get the blue screen and dump it said memorial on the disk (crash) i looked back and said svchost was at fault, but has also said that my anti virus can do so if theres more than one way now experianced with the most equipment and software conflicts, but it surprised me that makes the file to become unstable and if his currupt how can I repair the file because it is a system file i belive i didn't make a backup disk and my PC did not come with a spare windows vista disk files are in want and mp3 mov formats which i think the accident mov files that I can read them without problem please help me