Your login attempt was unsuccessful due to an invalid parameter. Avaya One-X

If you are working in Avaya One-X Agent or Communicator, you suddenly receive an error message.

If you are unable to click “OK” to the error message, end Avaya One-X by right-clicking the application icon in the task bar and choosing exit or by using Task Manager to forcefully quit.

Reference this Avaya article regarding a patch to fix the error.