I've occasionally been getting errors on startup recently referring to missing AiA .pbo's, namely one that was called "AiA_water2destroyer" or something similar (I think) but upon looking through the All in Arma folder I couldn't find the .pbo it was referring to. The game ran as fine as it normally does, I'm still getting the mysterious floating "water line" on many custom terrains including Namalsk and Podagorsk (which is why I was curious about this "missing .pbo"). The weird part is that sometimes The error appears and sometimes it doesn't... If I remember correctly the other pbo I had this pop up with was related to Characters, maybe CA_Characters.pbo but that wouldn't be from AiA I don't think.
Running Stable build A3 Beta, using Play With Six to launch.
I'll see about getting more accurate info on the pbo names.