Jamie E
might be stuck ssh sessions - especially if you have any scripts around that log into the controller which may not be exiting gracefully. Please run
show loginsessions
if you see a whole list of sessions, you can try the following from the console
process restart sshd
which will restart sshd and clear things up. Restarting sshd will cause the controller to be unreachable for about 30-60 seconds.
if you see that there are just 1 or 2 sessions in the list and you are getting the error you mentioned, then append the word "core" to the process restart above, restart it - see if it recovers, then raise a case with the corefile as to why you got locked out before you hit full sessions
regards
-jeff