Have you tried replacing your zombie.str that came with the mod tools again?
:please: I don't even know what that is.Go to your raw\english\localizedstrings
Go to your raw\english\localizedstrings
and you'll see zombie.str. Open it with a text editor and see if the top of it looks sort of like this.
Chances are, this isn't whats causing your problem considering you don't know what it is, I'm assuming it's never been modified.
(http://puu.sh/jcWBl/a7d88851f9.png)
EDIT: Make sure in your zombiemode.gsc it looks like this.
(http://puu.sh/jcWUe/ddaa9b3910.png)
I had this issue and i know a few others who have too, and frankly the only answer we found was reinstalling the mod tools
however, i know a lot more now, if you have a playable version of the map, send me a link and ill check in DEV mode and go through the IWD if you want
Seeing that I just installed this set of mod tools, I wI'll try to avoid that solution until all other options have been exhausted.i had to reinstall about 10 times before i finally got a properly set up version lol
Like I said, I'm not at my PC now but I will sent a playable version over later/tomorrow if another solution doesn't present itself.
lol no idea how, unless you used my pre-edited weapons gsc maybe lol
glad its working for you :)