Server Error in drop-downs

[adfitzge]

Why do I keep getting a Server Error when trying to update my drop-down menu on this website http://www.dwuathletics.com/.

Under the "Baseball" drop-down there are 2 "Stats" options that need to be deleted. "Baseball stats" is the correct link, and the only one I'd like in the drop-down but every time I try to delete the other two, I get this error.

"Server error
The website encountered an error while retrieving
http://www.dwuathletics.com/wp-admin/nav-menus.php. It may be down for
maintenance or configured incorrectly.
Here are some suggestions:
Reload this webpage later.
HTTP Error 500 (Internal Server Error): An unexpected condition was encountered
while the server was attempting to fulfill the request."

PLEASE HELP; I NEED TO GET THIS FIXED!