when i try to enter to my flash disk , i got these error : the System responsed : org.freedesktop.DBus.Error.AcessDenied : A security policy in place prevents this sender from sending this message to this recipient , see message bus configuration file (rejected message had interface "org.freedesktop.Hal.Device.Volume " member "Mount" error name " (unset) " destination "org.freedesktop.Hal")
I think this problem is connected with apparmor, which was added to Ubuntu fairly recently. It seems a horribly complex thing to me (maybe because I haven't had time to look at it properly). If you search for tips on how to put apparmour in "complain mode" you should be able to make it work. I can't give any more detail, because I can't remember how I did it when I was having problems with my printer, but you should find plenty out there with the details.