Click on the arrow next to hkey_current_user to minimize all the entrys.
Installing the games will take awhile some come back in about 10-20 mins.
Do the same thing for the other testapp folder.
Windows vista 7 and windows 8 users type in regedit in the start menu.If you quick launch icon windows 8 come across the same error again you didnt follow my directions and you need to start all over again.Now look for Wow6432Node then delete any bohemia entry.This might take time time to find any files, so walk away for at least 5 mins.If steam opens close it after it updates, if it updates.P after you have typed in regedit open it, then you will see 5 folders that have "hkey look for "hkey_current_user" click on the white arrow left side of the folder next find software and click on the white arrow (do this to all the.Always do this when making a server that way if you mess something up you have a folder you can dedicate to server only and not messing up the actual game and having to reinstall it all over again.Once you found your back up click on the box to reveal the other boxes open them until you see arma2 or what ever name you named your back.Mine is testapp 3390 if you have a folder that has the same numbers click on them and look at the right side you should see to files that says default and steamkey, look at the steam key first 4 letters and numbers remember that.If you come accross the same error once again, your pc might need to be reinstalled (aka reformatted).
Select restore then select where every you backed up your game to for x64 bit operating systems C:programs(x86)SteamBackups and for x32 bit operating systems C:programsSteamBackups.Now look for hkey_local_machine, do the same in step 9(if you dont see any bohemia entrys please continue).Once you uninstalled all 3 apps arma2 arma2 OA and steam, go to your c drive by start click on computer or for xp my computer then click on c drive go to programs or for x64 bit operating systems x86 programs then look for.Uninstall steam following the same steps above.Look for hkey_current_USE then click on the arrow pointing to hkey_current_user then do the same for the following,hkey_current_usersoftware, then look for Interactive Studio.If it doesnt match close that key window down and do the same for operation arrowhead if you see the same 4 go back to regedit and delete that folder.You dont want the folder just the stuff inside.Quick Method, one quick way to do all of this is to go into your registry section and delete all the keys for steam.