Media Player Not Working Properly

I have problem with my videos. They are stored on my external hard drive and when i open the file where they are located windows says it needs to close the program. I never had a problem playing them in wmp before and i have restored my computer to an earlier date with the same results. I also have tried different media players and the only one that seems to play or view any videos is vlc. Most of the videos are avi but there are some mpg4. I'm also not able to burn dvd's.