I too had this problem out of nowhere and this is what I did to fix it.
1)Uninstall battleye via steam/steamapps/common/arma 2 operation arrowhead/expansion/battleye/UnInstallBE
2)Delete BEclient.dll from Appdata/local/arma2oa/battleye/
3)Delete BEService and BEService_arma2oa from Program Files (x86)/Common Files/Battleye/
4)Verify integrity of game cache with steam
5)Launch game with steam
NOTE: Just be sure to delete the battleye service from Program Files (x86)/Common Files/Battleye. I reinstalled battleye/arma2/arma2oa several times and finally when I deleted the BEService and BEService_arma2oa is when this fixed the problem for me.
Arma 2oa won't launch with battleye
in ARMA 2 & OA - TROUBLESHOOTING
Posted
I too had this problem out of nowhere and this is what I did to fix it.
1)Uninstall battleye via steam/steamapps/common/arma 2 operation arrowhead/expansion/battleye/UnInstallBE
2)Delete BEclient.dll from Appdata/local/arma2oa/battleye/
3)Delete BEService and BEService_arma2oa from Program Files (x86)/Common Files/Battleye/
4)Verify integrity of game cache with steam
5)Launch game with steam
NOTE: Just be sure to delete the battleye service from Program Files (x86)/Common Files/Battleye. I reinstalled battleye/arma2/arma2oa several times and finally when I deleted the BEService and BEService_arma2oa is when this fixed the problem for me.