Computer Freezes & A Tech Support Splash Screen Appears – What Should You Do ?

So your computer freezes and a splash screen appears urging you to call a number that appears to come from Microsoft – what should you do
First it has not come from Microsoft – you went to a webpage that was infected through the ads on the page.I have received calls again on this and people letting these ” so called tech support ” people logon to their computer – which you should NOT DO.