I don't think it was a Microsoft critical link but malware. Have a look in ad-ons and extentions, in Firefox, and disable or uninstall anything you don't recognise. Re-set your home page. Check programs and features for an unknown program and uninstall. Run Ccleaner's reg cleaner. Finally run Malwarebytes in safe mode then normal mode.
Surface Pro 4 UK release date, price and specs: Thinner, lighter, faster with new Type Cover and Pen