fourth_george@live.com

Pretty much the same thing for me too. Did you ever figure out a fix? One account is still unplayable for me and when I am done building another PC I wanted to have my GF play too with that account if I can get it working again.

You should be able to switch just the registry info. Hopefully the simple way will work. Run Arma 2 and Arma 2 OA with combined operations through your steam account and it should rewrite the registry. You can watch this video if you want to switch accounts on one computer, , I know this isn't what you are asking. But in essence it should work before you install the whole thing again. If you want to reinstall just do so through the steam library game options. One thing to know edit the registry info carefuly at your own risk.