This is an intermittent issue. Our 7750 switch will unexpectedly terminate a authenticated SSH session, sometimes several times in a row. Debugging SSH sessions show the log:
Security: SSH logout by un-authenticated SSH user from src IP x.x.x.x from src MAC xxxx.xxxx.xxxx from PRIVILEGED EXEC mode using RSA as Server Host Key.
The drops can happen several times in a row, even during the authentication process. Just now, i've had a console session going for over an hour. It's really random and weird.