BAMMER4444

Hello everyone, I'm currently having problems with the "Bad serial number given in setup" error. I have looked through the forums and have seen people with this problem, they always get the "go to regedit and delete the 2 ArmA 2 OA files then run as administrator reply" But whenever I try to delete the second ArmA 2 OA file I get this other error "Cannot delete ArmA 2 OA: Error while deleting key" And I can never find anyone who knows how to fix and get past that. I hope that someone can give me an answer soon I love to play DayZ, Takistan Life, and Wasteland, but I can't play because of this error. Also, Steam tech support has been no help so I turned to here.