Our users have been receiving the  The UserID, Password or Account is invalid error more frequently lately. Normally, I can reset the password and they are fine.
However, today I have a user experiencing the problem repeatedly after resetting the password. He is attempting to connect vi SQL Assistant and using Teradata .NET Data Provider.
The Message manual has this explanation:
Either the userid, password or account specified is not valid, or they are being used in an invalid manner or from an invalid location, and the requesting user is not allowed to log on.
Therefore I recommend looking for the root cause on the Teradata Database server side. I think the error should be logged in the system log or DBS.Software_Event_LogV.