Files "Common\air_acr.pbo" are not keys signed by a key account to play this game

[DragonTycoon 0]

I get a message saying "Files "Common\air_acr.pbo" are not keys signed by a key account to play this game, please delete them to play". I have no idea what to do here. This happens on EVERY server I attempt to enter. Some help on how to get rid of these damn files so I can play Dayz again would be great.

Thanks

[rushcrush 20]

I get something similar when I try to open inventory but I can still press ok and keep going on what I was doing.