Mozilla has just released Thunderbird 3.0.2 version few days ago and now Thunderbird 3.0.3 is out.

This new release only includes a bug fix related to missing folders and an empty folder pane for the users who got Thunderbird 3.0.2 update.

This is recommended by Mozilla to all of the Thunderbird users to switch over the newly released version either they have experienced the bug in previous version or not.