The MW3-DLC-1-Deactivator deactivates the first Modern Warfare 3 DLC; so you can play the regular playlist with ALL your friends again !
And afterwards you just re-activate the DLC again. Quick & Simple !
Zip file contains a .bat file for manual de-activation and an .exe for use with STEAM.
Read the README file for instructions how to use !
UPDATE 05-26 :
Modern Warfare 3 - PC Patch 1.13 > Fix for mismatching files error between DLC and Non-DLC owners (!)