Comment 12 for bug 153444

Using this script with the following commands totally fixed the shutdown problem.

I leave this I found in the forums, maybe the developers can include it to totally fix this BUG that it's present since Edgy.

To activate the script the forum members suggest this (I tried and works)

gunzip umountcifs.gz && chmod +x umountcifs

sudo cp umountcifs /etc/init.d/

sudo update-rc.d umountcifs stop 02 0 6 .