ned's blog
Far Cry 2 and Windows 7 
Far Cry 2 players that use any version of Windows 7 cannot auto download custom maps. Placing winhttp.dll from Windows XP into the game's \Far Cry 2\bin folder fixes this.

Windows 7 is not an OS that Ubisoft will support with regards to Far Cry 2 - link -

FIX SOURCE - discussion thread

Download winhttp.dll - LINK - 200KB