Share operation failed

All of a sudden, my iMovie doesn't want to share any movies. I change the location of where the file is saved and I've even tried to share it as a "file", share it to the theater, and even YouTube.

I've restarted and even deleted some large video files on my MAC.

The error says "the share operation "file" has failed. Video rendering error: -50.

Help?!!?

Thanks!