When did you add the user to those groups? Before or after seeing the error for the first time? Either way, a reboot should fix everything up quite nicely, or you can logout completely, log in as root, and do this:
Code:
/etc/rc.d/rc.wicd stop # if using wicd
/etc/rc.d/rc.hald stop
/etc/rc.d/rc.messagebus restart
/etc/rc.d/rc.hald start
/etc/rc.d/rc.wicd start # if using wicd
Then logout as root, log in as your normal user account, and all should be well.