How about providing some more information. You just logged in and all of the sudden that message pops up? Or was that message actually in a file? And if that message was in /var/log/?????.log then find out what other information was provided along with it. You really don't give _anything_ to go on for people to help you.
You have most likely set up a bash command in your profile scripts that isn't setup correctly. Check .bash_profile and .bashrc within the login directory.