Data Federator Designer Error

I have installed DF XI 3.0 SP1 Fix Pack 2 (12.1.2.0 (Build 904301732) ) on a Windows 2003 server (64 bit).

While logging in as sysadmin to DF Designer I get an error message " An internal error occured. Please logout."

DF Query server Administrator works fine without any error messages.

I have made sure the user has designer authorization DF Administrator --> User Rights.

Is there any additional configuration required to log into DF designer?

Thanks!

-Deepu