Bug 778319 is about a similar (if no the same) issue. Could you try the workaround described in comment #7?
"Solution (that needs manual intervention) that works for me
# ALT+F2 to go to the shell, umount /media && mount /dev/sdb /cdrom
(supposing that the flash drive is /dev/sdb)"
Bug 778319 is about a similar (if no the same) issue. Could you try the workaround described in comment #7?
"Solution (that needs manual intervention) that works for me
# ALT+F2 to go to the shell, umount /media && mount /dev/sdb /cdrom
(supposing that the flash drive is /dev/sdb)"