Click a non mounted partition on dock causes system hang

[mahesh]

I have 3 drives with different partitions all ext4, Ubuntu desktop is configured to show unmounted volumes.
If I click on a partition listed in the dock nothing happens, if i double-click the system hangs, only mouse arrow moves.
The .crash file seems point to gnome-shell.
This may be an old problem, usually my Ubuntu desktop is configured to NO show unmounted volumes.