I am trying to turn my account into root, by the command "sudo su -", but I am informed this.
I'm using ssh.
I had this issue gosh some time back...... (sorry to say longer then my memory goes)..... however I believe it had to do with the shell fork bomb protection....... login to server, security it is there. Try disabling this , then try again. You can always enable it when you are done.
Hope this helps!