I had to replace my operating system and hard drive because of a crash, and it was done at a computer shop. After working with this new Windows 7 for a couple of weeks, suddenly I'm getting messages that this is a counterfeit Windows. Of course I hate to replace it again because I've just fixed a lot of settings and replaced programs. It occurred to me that I don't know whether the messages may be fake, some kind of malware, how would I know? (I don't know much...) Why would the messages have started after two weeks? What is my best course of action?