I recently upgraded to a faster server. Since then I have noticed several videos uploading with 0:00 duration and will not play. I do not believe it is a problem with the videos themselves as the 0:00 duration has shown for videos uploaded by different users and only began after I recently upgraded to a faster server. How can i;

1. Fix the existing videos with duration 0:00 so they function normally on the site.
2. Prevent future videos experiencing this problem?

Many thanks