Malware hopped on from a page you visited. It could be a Trojan, or a typical ransomeware package, and it could have a long "fuse" before obvious problems occur. If your browser seems to work okay, visit your OS support site to review how to partition your HDD. Back-up copy all your valuables to cloud and do the partition. Or, DL and install AVG or another constantly updatable anti-viral suite to scan your entire HDD, because it could also just be a fairly innocuous "come on" adware bot.