If you right click on a drive icon and go to properties then the volume or drive tabs, under the settings dropdown, there is a place to type mount point, options, and file-system type.

When typing in the mount point, if any type of not-permitted characters are put in it, it should warn the user that they can't use those characters. Some users might put a whole file path into that field (ie, /media/storage) and then unmount and on remount, it fails with an error message saying that slashes are not permitted in the mount point. It should warn about this BEFORE a user can get out of the dialog box.