Error Message : Error authenticating user. Arithmetic operation resulted in an overflow. 

Stack Trace:    at Midas.Midas.LdapAuthentication.IsAuthenticated(String domain, String username, String pwd) at Midas.Default_Page.  authenticate(String username, String pwd)

I would suggest looking at the following page

https://connect.microsoft.com/VisualStudio/feedback/details/681135/system-directoryservices-arithmetic