Backtrack 4 pre-final: AutoScan Network in the menu located under Backtrack > Network Mapping > All does not seem to run with a user unless one edits the menu item and click the box that says run as different user, then add root as the username.
To edit the menu item right click on the menu select menu editor, edit ,save, exit.
This is not so much a bug, but some people who try to run it may notice that it will not connect to the lo interface without root privileges and then give an error.