Unchecking does nothing on my system, I too run this on XP. It just fails regardless, only replacing my dll everytime I want to play, can I then get on a server.
Okay I got it working!
1. Delete everything Battleeye from OA
2. Verify local cache with steam.
3. Replace BEClient.dll and BEServer.dll with ones from battleeye.com
4. launch Arma 2 OA with the ArmA2OA.exe (not with steam)
For DayZ
5. Open dayzcommader and uncheck the option to launch arma 2 with steam in the settings.
6. Update Arma with Dayzcommander
7. Repeat step #3
8. Profit!
It seems as long as I don't run with steam it works.
I have the same problem. When i verify the arma install from steam I get windows cannot find ArmA2OA_BE.exe, but i can see it in the folder. If i run as admin it say battleeye failed to install. I have no firewall and no antivirus running.