Thank you all for responding so quickly. Windows Defender has completely scanned the computer and detected two Trojans. I am convinced and your answers that these ads came from those viruses. Anyway I have also installed in Google chrome an anti-pornography and anti-ads program and the truth is that I am very happy. It works whenever I search the internet. Thank you very much with all my heart. Andy, Scorpio and Don, take care of yourself: Your friend Jorge
.