how do i clean my mac of viruses

Your removal of Mackeeper may not have been complete.

There are at least two schools of thought expressed by experienced users here in this Apple community regarding malware and popups.

One school primarily uses free application(s); the second school requires no additional software and just some simple steps on your part.

Read these (of many threads) discussions.

Yosemite OS X & MacKeeper I can't unistall

Got a malware on OS X Yosemite, how do I get rid of it?

"Ransomware" web pages

Pop up problems in Safari on OS X Yosemite!

See these Apple notes:

Remove unwanted adware that displays pop-up ads and graphics on your Mac - Apple Support

Safari 8 (Yosemite): Security pane of Safari preferences

OS X Yosemite: Protect your Mac from malware

1. Use free AdwareMedic to remove adware

http://www.adwaremedic.com/index.php

Install , open, and run it by clicking “Scan for Adware” button to remove adware.

Once done, quit AdwareMedic.

or

Remove the adware manually by following the “HowTo” from Apple.

http://support.apple.com/en-us/HT203987

2. Safari > Preferences > Extensions

Turn those off and relaunch Safari.

Turn those on one by one and test.

MacKeeper removal:

http://applehelpwriter.com/2011/09/21/how-to-uninstall-mackeeper-malware/

You inadvertently installed adware. You do not need to download or install anything to fix it.

For a description of how this may have occurred, how to avoid it in the future, and for Apple's recommended actions read How to install adware. Apple's instructions are linked in the Recovery Procedure near the end of that document. Read and follow them carefully. Pay particular attention to the easily overlooked passages directing you to restart your Mac when required.

MacKeeper didn't cause the problem, but it certainly can't help. Once you are deceived into installing adware, its mission is to convince you to install even more junk, exacerbating an already bad situation. Make sure MacKeeper is really gone, and then eradicate the adware by following Apple's instructions linked in the above User Tip.

Back up your Mac before making any changes to its file system. To learn how to use Time Machine read Mac Basics: Time Machine backs up your Mac - Apple Support.

There is no need to download anything to solve this problem.

You may have installed one or more of the common types of ad-injection malware. Follow the instructions on this Apple Support page to remove it. It's been reported that some variants of the "VSearch" malware block access to the page. If that happens, start in safe mode by holding down the shift key at the startup chime, then try again.

Back up all data before making any changes.

One of the steps in the article is to remove malicious Safari extensions. Do the equivalent in the Chrome and Firefox browsers, if you use either of those. If Safari crashes on launch, skip that step and come back to it after you've done everything else.

If you don't find any of the files or extensions listed, or if removing them doesn't stop the ad injection, ask for further instructions.

Make sure you don't repeat the mistake that led you to install the malware. It may have come from an Internet cesspit such as "Softonic" or "CNET Download." Never visit either of those sites again. You might also have downloaded it from an ad in a page on some other site. The ad would probably have included a large green button labeled "Download" or "Download Now" in white letters. The button is designed to confuse people who intend to download something else on the same page. If you ever download a file that isn't obviously what you expected, delete it immediately.

Malware is also found on websites that traffic in pirated content such as video. If you, or anyone else who uses the computer, visit such sites and follow prompts to install software, you can expect more of the same, and worse, to follow. Never install any software that you downloaded from a bittorrent, or that was downloaded by someone else from an unknown source.

In the Security & Privacy pane of System Preferences, select the General tab. The radio button marked Anywhere should not be selected. If it is, click the lock icon to unlock the settings, then select one of the other buttons. After that, don't ignore a warning that you are about to run or install an application from an unknown developer.

Still in System Preferences, open the App Store or Software Update pane and check the box marked

Install system data files and security updates (OS X 10.10 or later)

or

Download updates automatically (OS X 10.9 or earlier)

if it's not already checked.