Comment 18 for bug 26338

This solved the problem to a large extent:

taken from this thread:

http://www.ubuntuforums.org/showthread.php?t=81836&page=2&highlight=hal+automount+usb+problem

Originally Posted by pbrockway2
Hi,

I've been getting the same error as the OP (Error: given UDI is not a
mountable volume) for about 36 hours. I've been setting up 5.10,
changing lots of things, and don't know at what stage I lost USB access.

Following a suggestion in one of the threads mentioned above, I
had a look at the group membership of the "hal" user. In particular
I set the following rights:
Enable access to external storage devices automatically
Use CD-ROM devices
Use floppy drives

(The thread I was reading referred to actual group names, but these
seemed to correspond).

After a reboot my USB key appeared on the desktop! I hope it stays there
and that this may fix the woes of others - as a "quick fix" checking the hal group
membership beats reformatting the USB key (which I did), or reinstalling
Ubuntu (which I was contemplating)...

Cheers,

Peter

It seems that adding the new user or changing my password (I did both at the
same time affected the permisssions associated with the 'hal' group.

Only thing remaning is associating dvd with totem which is still stuffed up, not
a problem.

Hope this helps somebody and cheers for your time Martin.

Rick....