You had the fix but you put it in the wrong ini file. Multibounds is only used in one cell; the Lucky 38. The devs tanked the entire GECK just to get that one cell to work, but you can fix it. Go to Documents\My Games\FalloutNV and find geckcustom.ini. Make a copy of it as a back up. Open the orginal with NotePad.
In the [General] section find the line bUseMultibounds. Change it to bUseMultibounds=0. IF you have problems with the Lucky 38 set it back to bUseMultibounds=1.