Windows Explorer Error Message

I've never had this problem until about 2 or 3 days ago.
I have a folder where I save all my avi and mpeg movies.
I was able to open this folder and reanme the files and
work with these files just fine. Now for some reason
unknown, I cant. Everytime I click on my MOVIES folder
when it goes in it seems its going to work but once it
starts opening the thumbnails, I get the message: Windows
Explorer Has Encountered a Problem and Needs to Close.
Please forgive the inconvenience....etc etc etc...I still
have 45.5 gb of space left on this drive so I know its
not lack of space....What can I do to resolve this
issue???