Q: i think my mac might have a virus on my imac as i never used to get pop ups and adverts and is running slower and sometimes freezes and shuts down what should i do?

Not a virus but pop up ads can be handled very effectively by getting AdwareMedic from Thomas Reed's site: http://www.thesafemac.com  Tom is a regular contributor on here and has written a great program to get rid of those ads.

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I don't mean to hijack this post but I am having a problem and can't seem to post a question.  Today when opening safari I got a pop up screen that said Safari-Alert  Suspicious Activity Might Have Been Detected.  Major-Security Issue

To Fix it please call Support for Apple

+1-866-782-98** (Toll Free) immediately

I deleted the last 2 digits so no one would call it and get charged a million dollars.  I tried to reset Safari but the options are all grayed out.  I tried to delete to reinstall but it says I can't delete.  I downloaded a malware program suggested on here and it found nothing.  Any suggestions?

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Force Quit .

Press command + option + esc keys together at the same time. Wait.

When Force Quit window appears, select the Safari if not already.

Press Force Quit button at the bottom of the window.   Wait.

Safari will quit.

Relaunch Safari holding the shift key down.

Thank you so much!  I tried to post my own question but couldn't get it to go past the post question.  Frustrating day.  Thanks again for your help.