When using steam, more specifically dota 2, IE popups would apear at the background and also in steam browser its self there would be popups and ads. after a while it started happening to chrome where it opens a new tab leading to an ad. i am using adblock as well so it was a big surprise when it appeared. i reinstalled chrome and its still would popup. after some research i did a DNS flush and it stopped happening to chrome. but steam still happens. Before the DNS flush some sites leads...
Steam and chrome malware popups
Steam and chrome malware popups