If you’ve upgraded your Ubuntu VPS to 8.04 check your syslog. It could happen that getty processes are being killed all the time:
May 2 06:28:54 vps_server init: tty3 main process (19690) terminated with status 1
May 2 06:28:54 vps_server init: tty3 main process ended, respawning
May 2 06:28:59 vps_server init: tty6 main process (19753) terminated with status 1
May 2 06:28:59 vps_server init: tty6 main process ended, respawning
May 2 06:29:00 vps_server init: tty5 main process (19764) terminated with status 1
May 2 06:29:00 vps_server init: tty5 main process ended, respawning
May 2 06:29:00 vps_server init: tty1 main process (19772) terminated with status 1
May 2 06:29:00 vps_server init: tty1 main process ended, respawning
May 2 06:29:02 vps_server init: tty4 main process (19891) terminated with status 1
May 2 06:29:02 vps_server init: tty4 main process ended, respawning
May 2 06:29:02 vps_server init: tty2 main process (19892) terminated with status 1
May 2 06:29:02 vps_server init: tty2 main process ended, respawning
...
To get rid of this (you don’t need terminals on remote machine) edit files /etc/event.d/tty1, /etc/event.d/tty2, etc and comment lines that causes respawning:
respawn
exec /sbin/getty 38400 tty1