After installing the CoD4 1.6 patch and joining a CoD4 server you get the "code_post_gfx_mp.ff different from the server" ERROR screen.

Check if you have 2 folders in your zone folder.

Standard path is C:|Program Files|Activision|Call of Duty 4 - Modern Warfare|zone

Copy all into english folder.

Example :

Copy everything from |zone|german Folder into |zone|english Folder.

If correct problem solved.