QICKTIME PLAYER DOES NOT WORK

Hi everyone!!! I'm having a problem with my Mac OS X 10.8.3

The Quicktime player on my mac does not work. Everytime i open the video it appear to be "Quicktime player quit unexpectedly". No matter how i try to open it, it still does not work.

It works perfectly fine before but after i inserted a disk and tried to open AVI file through Quicktime, this happened. I was wondering whether the AVI file was the main cause of this problem. Please help me out!!!

\The picture above is what it shows whever i open a video.