independence@titan ~ $ screen -r There is a screen on: 8541.pts-0.titan (Dead ???) Remove dead screens with 'screen -wipe'. There is no screen to be resumed.
This means that your screen has been killed while you were away. Probably because of a server reboot or similar. Just type 'screen -wipe' and then start a new screen.
If you want your screens to automatically restart when the system boots up after a reboot, read this howto on autostarting apps: Howto/Autostart.