Login Error 3004-304

I am trying to log on and get an error "3004-304 You are not allowed to login at this time.". This happens with both "root" and "admin" (the only other user ID on the system). System console or telnet session, doesn't matter. When I reboot the system, which I can only do with the power button since I can't sign on to issue shutdown, I can again log on, but after a day or two the problem returns. The system is obviously still running because I'm not having any problems with TSM backups. Google turns up nothing. Does anyone have any ideas?

Thanks,
Dino