You've just munged your map, and when you start up BF2, load the map, every thing is called null!!! Null this null that. you get point. So now your wondering how to fix right? Well this happened to me I found and I way to fix this. So now sit back and read this faq as explain to you how to fix this. Oh, one more thing. replace abc with you three letter world name.

1. Remove the abc folder from the world folder and put on your desktop. Rename the folder to abcw.

2. Remove the abc folder from your script folder found in the common folder and place it on the desktop.
Rename it to abcs.

OP3. If you made any sides, remove them from the sides folder and place it on the desktop.

4. Delete data_abc.

5. Now for the MOST IMPORTENT step. Rebuild you world. Go to data, then _build, then click Modtools VisualMunge and name the world abc. After it's been built, place the abcw folder in the world folder. Delete the abc folder and rename abcw to abc. Then, place abcs in the script folder. Delete the abc folder and rename abcs to abc. place the your side in the side folder if you made one. Now munge.

So, how did this happen you ask? Well, you've must've been lazy and renamed something in the local tool. Now by rename I mean like this: rep_weap_{inf_rifle} to {inf_blaster}. Don't know why it makes this error, but it does. So now you how fix this, and its probably best to do this fix last. So now hopfully some maps I've played that have this bug will get fixed and finally, your welcome if this works.

Uh, that error has to do with the Edit Localize tool, and how you setup the localizations.
It has nothing at all to do with your world, or any of that other stuff, you just have to setup whatever is called [Null] properly in EditLocalize.bat.