" error: db4 error(16) from dbenv->remove: Device or resource busy"
The problem may be that you have an old rpm lock set so that the rpm data base is perpetually locked. See if you can find a rpm lock file and delete it. Try:
find /var/lib/rpm -iname "*lock*"
find /usr -iname "*lock*"
Remember that there are a lot of lock files for things other than rpm so be sure that you have found the rpm lock file before deleting it.
Be prepared. Create a LifeBoat CD.