Redmine

I have a folder on the DSMF plug-in called 'Training'. A PowerPoint file inside of 'Training' was edited and one of the revisions was deleted. After this the entire 'Training' folder stopped working. When I try to enter the folder it says:

"Internal error

An error occurred on the page you were trying to access.
           If you continue to experience problems please contact your Redmine administrator for assistance.

If you are the Redmine administrator, check your log files for details about the error."

And if I try to delete the folder it says:

"Folder is not empty"

I have attached 2 files that are both posts from the production.log. One is the output when trying to enter the folder (enter_folder_error) and the other is the output when trying to delete the folder (delete_folder_error).

Any help is greatly appreciated.