The Battlefield 2 1.5 patch causes multiple things to break in Allied Intent Xtended 2. However, one of the AIX devs, Ti_GER arn354, has made a hotfix that should fix these problems when you are trying to play co-op. The changes are:
The deployable mortar has been disabled - any attempt to select it will result in the previous weapon being re-selected.
BF2 1.5 online, no ammunition magazine may contain more than 1023
rounds. The AH-1X, A-10, A-10b, AH-64, AH-64 Gunship,Rooivalk, Yak-38
and Blizzard all broke this rule by varying degrees, but now have a
maximum of 1000 rounds in the offending magazines. A side-effect is that
the ammo-bar for an affected magazine will only fill up to the level
set by the new 1,000 round limit, and so may not look completely full.
Please read further information about it and download it here: Battlefieldsingleplayer.com