Custom Security Extensions for SQL Server 2008 R2 - "Temporary User issue"

"The remote server returned an error: (500) Internal Server Error." for the first time click from my application, for the second time click the report Home page gets loaded. When i tried to log the custom security extension code, on the first click we are getting "Temporary User" in GetUserInfo() method, so as its not a valid user to get the access we get http 500 error on the screen.

How to handle temporary user in custom security extension code so that we can avoid the Http 500 error before it loads with proper sign on user.

Any suggestions or ideas much appreciated.

Thanks,

H.