When using my Firefox browser, I get the message that my computer is locked and a number to call. It sounds like the old Microsoft scam. They don't even know what operating system I am using. No, I am not telling them, but I can't use the FF browser. The only tech in my small town that understands Linux is unavailable. I've read that browsers can be infected while the computer is not. I don't know enough about this to help myself. Can someone advise ?