Slow Computer message

On my Imac using Safari I get a pop up message saying"My computer is running slow and you must run a program. It doesn't give you a choice to close this message except to force Safari to shut down,then when you get on Safari it pops up again. What should I do? Thanks in advance!

Firstly, it's malware. I would download Malwarebytes Anti-Malware and run it and see what it comes up with. It sounds to me as though it could be Mackeeper. Whatever you do, do not download Mackeeper. It's rubbish and in itself is Malware.

Try Malwarebytes and let us know how you get on.

Could be "ransomware".

- Turn off your computers wifi.
- Quit Safari.
- Reopen Safari.
- Turn WiFi back on.

Hopefully the problem is gone.

- Nick

Thank you Gandalph I will check out "Malwarebytes"

Thanks Nick will give it a try.

Follow nick's advice - you have no malware - yet - it's a browser hijacker easily elminated by disconnecting from the web so that it cannot download again.

It won't hurt anything to run Malwarebytes afterwards for your own peace of mind.

FYI: When a user is in this situation, they cannot download Malwarebytes nor anything else.
Their browser has been hijacked.
They must get rid of the hijacker first by closing the tab that web site is loading in.
After Force Quitting the browser:
For most, disconnecting the wifi or ethernet cable is easiest - because then the hijacker can't load and you have time to close all the tabs normally.
If you are fast enough, you can close the offending tab when you reopen the browser before it has a chance to load the hijacker.
A 3rd way is to simply hold down the shift key while you launch Safari.