Do you have the file /usr/share/hal/fdi/policy/gparted-disable-automount.fdi ? If so try removing it and reboot. If it works this is due to bug #134712.
Do you have the file /usr/share/ hal/fdi/ policy/ gparted- disable- automount. fdi ? If so try removing it and reboot. If it works this is due to bug #134712.