Since at least a month, my 11.10-64bit PC doesn't shutdown anymore from the GUI. It simply freezes on plymouth screen. If I open gnome-terminal and type "sudo poweroff", it shuts down correctly.
This is very annoying. I don't have any relevant message in the logs. It simply stops at "The system will be halted"…but it doesn't power off.
Best Answer
I have fixed this by adding the following line to the file /etc/default/halt:
INIT_HALT = POWEROFF