Q: Message on MacBookAir: www.rrtd-malware.com Your Apple computer is blocked

That's a scam. Choose Force Quit from the Apple menu, close Safari, and then launch it with the Shift key held down; if the message reappears, disconnect the computer from the Internet and close the tab the popup came from.

(139215)

Apple does not send messages like that...

That is evidence of the scam. Don't call it.

That message and phone number is not Apple.

If you have reason to, you could

Contact Apple from their web site:

http://www.apple.com/support/contact/

Note next link covers phony tech support scam & how around issue:

Phony "tech support" / "ransomware" popups and web pages

And the OS X does not warn of what does not affect it.

• Stop pop-up ads and adware in Safari - Apple Support

The phony tech support scam is an enticement to get people

to call and tell them yes, unlock my mac and steal my ID and

also while in there, take my AppleID, brick my mac, and toy

with my accounts and personal information, too. Don't do it.

• U.S. iPod, Mac and iPad technical support:

(800) APL–CARE (800–275–2273)

http://www.apple.com/contact/

{The scammers also like to get you to pay, too, to allow them

inside your Mac to mess you up & rob you further. Avoid it.}

Good luck!