Virus or scam?

Hello, I signed on to this forum to get an answer about something that's just popped up on my home computer, which currently runs OSX 10.7.5 (we're planning to upgrade soon).
I share this computer with my partner. He usually uses Safari as a browser on his "side". Today he got a frozen screen and a message about something called the Zeus virus, referring to MicroSoft.
The thing is, we don't have anything from MicroSoft installed and never have had. Everything I've read about Zeus seems to refer to it being a MicroSoft problem. He hasn't clicked on any bad links that he knows of, and when he switches over to Opera there are no problems, and I haven't had any problems since restarting and logging into my side.
Is this a scam? There is a 1-800 number listed on the virus message. I'm going to assume it's a scam until proven otherwise.

It is a scam as there are no Mac OS X viruses. Don't ring. Close Safari and turn off your modem/router, and then power back on and everything should be okay. Very wise to update to El Capitan as Lion OS X.7 has not been supported by Apple for some years, so no more security updates. Download and run Malwarebytes for Mac to help fighting malware.

Also AdblockPlus and Ghostery are great extensions to run of Safari.

Thanks, I thought that was the case.

Hope the OP comes back...

You could post the specs of your computer to have someone tell you how far you can go with an upgrade.