10.04 systems hangs during shutdown

Hi,
When I attempt a shutdown the session gets logged out and I getb the Ubuntu logo with the five dots going successively red to white underneath. The colour change goes for around 7 dots (sometimes more or less) then the system hangs. Have had to power off. Not sure where to look for logs.

Have done a number of things lately to sort out a Grub2 problem (see 171612) so suppose that's where the problem lies.

Cheers, Bob.