I have had the same problem for a few days now. The latest updates for the system tools contained a modification of the way in which they use gksu to access system files. I didn't take enough notice of the changelog to work out exactly what the changes were but a workaround is to edit the menu items and put gksu in front of the entries.
I am running Edgy and it works fine on a clean Edgy install but the updates kill it. It appears that the update is a Debian update. -- Cannot run many system tools https://launchpad.net/bugs/71507 -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
