Is MacKeeper legitimate or a scam?

One of the worst. Contact Earthlink.

Force Quit Safari ( command + option + esc keys).Then restart Safari holding the Shift key. If you still have problems Empty Caches (Safari menu > Preferences > Privacy > Remove all website data. (This will also remove history if you do not want to remove History open Safari Preferences > Advanced and check mark “Show Develop Menu” then choose “Empty Caches” from Develop Menu ).

Then go to Safari Preferences > Extensions and check there. If there is an extension delete it.

If the problem persists then download and run Malwarebytes. Malwarebytes was developed by one of our own colleagues here in ASC and is about the most proven anti-malware software for Mac.

Hi,

Scam ... you do not want MacKeeper on your Mac. It's useless.

Avoid phishing emails, fake 'virus' alerts, phony support calls, and other scams - Apple Support

If you are using Safari, go to the Safari menu bar, click Safari > Preferences then select the Security tab then make sure: Block pop-up windows is selected.

MacKeeper – Do Not Install

MacKeeper – Do Not Install (2) See SDW2001’s post

Safari – Popup takes over

Safari – Popup takes over (2)

Popup remover – Scam Zapper

If the pop-up reloads, force quit Safari (command - option/alt - esc) and reopen with the shift key held down. If that doesn't work, disconnect from the Internet, go to Safari/History and delete the website. Quit and reopen with the shift key held down. Then reconnect to the Internet.

Safari -Tech support scam pop-ups

You're welcome.