Sometimes clicking on the Enable button in WHM does nothing, when trying to enable Shell Fork Bomb Protection (SFBP). SFPB is, to quote cPanel's official documentation, a feature that "will prevent users with terminal access (SSH or Telnet) from using up the system’s resources and potentially crashing your web server via a malicious attack known as a fork bomb.
In order to enable Shell Fork Bomb Protection, the /etc/profile file must be editable. Enter this into root to check the write status:
If the file has -i on it, then it will need to be made mutable to be edited for this service. Type this into shell to make that change:
chattr -i /etc/profile
As per cPanel staff @ http://forums.cpanel.net/f34/i-cant-...on-224071.html
/ Note to self.