If the machine is so hosed as to prevent you from logging in at all, do the following. This will boot the machine single user. You should then be able to fix whatever else was broken.
Machine seems hung.
Then retry the mount, or reboot the client. Too many users logged in. It should typically be correct within 1 second. If it's off by more than a few minutes, Kerberos login encryption will fail. Ops- you should make a note of this in your EOS, or notify the sysadmin if you have to do this.