My computer was blocked and a message said: "Do not ignore this message. Immediately call 877-522-7560." The person who answered lead me to believe he was an Apple tech support person (my computer is an Apple), and he said I needed to install anti-virus software to prevent hacking into my on-line financial information. He then started doing things to my computer on-line (installing anti-virus software, etc.) and suggested I contract for tech support. I authorized the charge of $299.99 to SM Technologies of Fairfax, VA, but the next day I took my computer to the Apple store. They ran a test of my computer, said there had been no problems, that anti-virus software comes installed on all Apple computers, and that what I was told by the SM tech was nonsense and a scan (and he even left my firewall down). I called SM Technologies and demanded a refund. They promised to provide one, but have not done so for 13 days.