Same problem been playing all week on patch 1.25 installed and got that error message. Tried widescreen fix as in adding  +szx 1440 +szy 900 to the mod target, same error. Un installed mod played 2142 no problem Installed mod,restarted pc and same error.

i used the torrent link from this site as the aus mirror wasnt working at the time might try again ey

Ok I got it to work.. hope this works for you guys (its messed up).  Delete the mod and reinstall.  When its asks where, the default is something like program files/ea/battlefield 2142/
1. add 'mods' to the end of that. 
2. start up the mod... it will ask where the 2142.exe is... browse and find it.  It will start then crash.
3. go into the mods folder and you will see 'bf2142', 'first strike' and another 'mods' folder.  Go into the second mods folder (which is the one you created) where you will find another First Strike folder.  Cut everything inside that folder.
4. Go back out and paste everything into the First Strike folder located in the 1st mods folder.
5. Delete the empty mods folder.
6. Click on the short cut to start the game.

In my opinion... something is happening with the creation of the settings folder upon the automatic duplication of your profile (which is located in the settings folder) upon starting up the game for the first time.  I know its confusing but it worked for me.  I'm gonna play the game now fellas, hope I was able to help you.