Progress: ERROR: 0 while uploading new videos

I have a problem with the newly installed vShare for my site. When I'm uploading a video, it gives me the error message ERROR:0 next to the Progress:, where the progress bar usually is. Also, when it's done uploading I get this message on the screen:
Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

Have you got any idea how to fix this? Thanks!

Open a Support ticket with your site admin and FTP login details.

Thanks,