Error 500 while logging in

server error log shows “[Mon Apr 11 11:22:53 2011] [error] [client 122.170.50.254] File does not exist: /home/mudesign/public_html/500.shtml”

browser while logging in shows “Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, webmaster@mudesign.in 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.”