Nautilus disable auto mount
From WickyWiki
When you insert an USB stick or USB drive Nautilus will automatically try to mount every partition on it. In combination with 'Require sudo password for mounting', it will request a password for each try. You can disable this behavior with the gconf-editor.
Start gconf-editor:
gconf-editor
Go to: apps -> nautilus -> preferences -> media_automount and uncheck the value.
See also: