I got the same errors as Harald after trying the above. It was still very slow to shutdown and sometimes didn't shutdown at all.
The only way I could previously get it to shutdown reliably was with a "sudo shutdown -h now".
I have now found if I remove the network manager it completely fixes it. I now have no errors and quick shutdown.
sudo apt-get remove network-manager
If I re-install the above network manager, the problem comes back. So that is definitely the cause in my case.
I have installed "wicd" as a replacement network manager. I did this before removing the Ubuntu supplied network manager.
I am using 11.10 that has been upgraded from 11.04. I have wired ethernet.
I got the same errors as Harald after trying the above. It was still very slow to shutdown and sometimes didn't shutdown at all.
The only way I could previously get it to shutdown reliably was with a "sudo shutdown -h now".
I have now found if I remove the network manager it completely fixes it. I now have no errors and quick shutdown.
sudo apt-get remove network-manager
If I re-install the above network manager, the problem comes back. So that is definitely the cause in my case.
I have installed "wicd" as a replacement network manager. I did this before removing the Ubuntu supplied network manager.
I am using 11.10 that has been upgraded from 11.04. I have wired ethernet.