Comment 73 for bug 204133

$ cat /proc/cmdline
root=UUID=B654EB6554EB26B9 loop=/ubuntu/disks/root.disk ro quiet splash

I am also facing the same issue. Upgraded the system to 9.10 from 9.04

Once I hit the shut down the black screen displays

Stopping Kernel oops catching service kerneloops
Stopping the winbind daemon winbind
Shutting down ALSA
Asking all remaining processes to terminate
Deconfiguring network interfaces
Deactivating swap
[25490:712192] Buffer I/O error on device loop0, logical block 3002840
This happens every time and I have to hard shut down the PC using power button.