vncserver session doesnt reboot properly

[compdoc]

When I log on remotely using VNC to an 11.04 machine, and choose the Restart
from a menu, or, when I update the machine with Update Manager and click
Restart, the computer never reboots.

All that happens is that the desktop (gnome) quits, and the computer sits
there. Or if the Update Manager was running, it remains running.

Issuing 'sudo reboot' works, as does 'sudu shutdown', etc.

Whenever I forget and ask Update Manager to restart after an update, I have
to log in with SSH to issue a reboot. I can't even seem to switch to a text
console using VNC.

Any help would be appreciated,

Thanks