It could be very annoying that you keep getting the message asking you to call for tech support at 1-877-712-3635 while using the browser. This pop-up displaying scary alert and locking up your screen actually is a tech support scam used to cause distress and make users to contact the swindlers via the line 1-877-712-3635. You could be driven nuts by this bogus security warning shown and ‘Critical Alert from Microsoft’ audio alarm triggered.