We recently ran accross a problem while mounting an HFS+ drive on Ubuntu Desktop (Hardy Heron) and fortunately were able to find a quick fix on the net.
While trying to mount the HFS+ drive with RW permissions, we specified the mount point “/media/MacintoshHD” and included “rw” as one of the mount options. Apparently, Hardy doesn’t like this very much and will refuse to mount the drive and returns the error each and every time you try to mount the drive. To fix this, open up the Configuration Editor by entering the following command in Terminal:
gconf-editor
The Configuration Editor opens up and shows you an easy-to-read two-pane window. On the left pane, goto system > storage > volumes and select the device listed. On the right pane you’ll see all the mount options. Delete all the values you see, exit Configuration Editor and disconnect your drive. Plug your drive back in and voila!
Now to get RW permissions on the drive…