First I'd wonder about a corrupted file or something giving you bad sig checks. Look at where you got them. Second, Ins server uses ver2 sig checks so it is harder to spoof. Third, when I had issues with my installs I eneded up uninstalling and doing this: -Install first cd/dvd/dlc game etc. -Run game and join a mp server. -Patch -Join a mp server. -next game addon. -Join a mp server. -repeat etc. This is the only error I could find in the logs. Every error so far has been the same. 16:45:43 Player =VG= SemlerPDX: Wrong signature for file addons\chernarus.pbo Found a link about your problem. It has to do with Ver2 checks and certain vendor copies of the game. http://www.realitymod.com/forum/f440-pr-arma2-general-discussion/102608-server-anti-cheat.html