MJZGaming

I emailed Bohemian Interactive and I received a list of possible solutions. I tried every one of them and after restarting my computer, I was able to play Arma II/DayZ again. I'm not really sure which solution worked, or whether it was a combination of multiple solutions. I hope this helps. "Hello, there are several possible fixes for this issue, please read carefully: 1) Please run the Steam application as Administrator: 1. Exit Steam. 2. Right-click on Steam icon. 3. Left-click on "Run As Administrator". 4. If the problem persists, reboot your computer and try the procedure again. 2) DELETE ARMA 2 OA REGISTRY ENTRIES 1. Exit Steam, open Start menu and type this directly into the menu (in Windows XP, you will have to click on "Run" first): regedit 2. Press Enter. 3. In regedit window, click on HKEY_LOCAL_MACHINE. 4. Press CTRL+F to bring up search. 5. Look for "ArmA 2 OA" (without the quotes). 6. Delete all the "ArmA 2 OA" entries you find from the registry. 7. Run Steam as Administrator. 8. Right-click on the game in Steam Library. 9. Click on "Properties". 10. Select "Local files" tab and click on "Verify integrity of game cache files" button. 11. Please wait, the process can take several minutes. 3) REINSTALL STEAM 1. Go to Steam's installation folder. 2. Delete everything there except "steam.exe" and "steamapps" folder. 3. Run "steam.exe" - Steam will reinstall itself automatically. 4) RUNNING ARMA 2 OA DIRECTLY WITHOUT STEAM 1. Go to Steam's installation folder. 2. Navigate to steamapps/common/arma 2 operation arrowhead. 3. Directly run arma2oa.exe (please note that you might not see the ".exe" extension)."

I am also having the same problem. None of the above solutions worked for me. It must have something to do with the computer unexpectedly shutting down and corrupting the key. I could play Arma 2 fine. The other day I was playing it and my power went out and the computer shut off as well. It was after that the "bad serial number" problem happened.