Fallout 3 Message Board  

*IMPORTANT*
For this to work, you must go into your FALLOUT.ini (located in "*yourdrive*:\Documents and Settings\*yourname*\My Documents\My Games\Fallout3", and change this line:
"bInvalidateOlderFiles=0"
to this:
"bInvalidateOlderFiles=1"

You also need to the check the box for this .esm file at startup screen, before you start the game. This is the box that pops up when you use Fallout 3 icon. Just click on files and you can see all of your .esm files, just make sure the box for this file is checked, along with the main file.

true as well. make sure you guys are doing this.

same as oblivion.