if you don't need all the opensource virtual box OSE stuff, you can get rid of it by doing:
apt-get remove virtualbox --purge
then check with dkpg --list|grep -i virtualb
to make sure no other ose packages exist.
Otherwise, you can find the config file like this (sorry, I don't have Ubuntu running in my Vmware right now):
dpkg --list|grep -i virtualb
dpkg --list-files for each package.
Alternately, just string it all together:
dpkg --list|grep -i virtualb|while read x;do dpkg --list-files $x;done
or however you prefer to do it.
Hope that helps. Sorry I couldn't be more specific.