Whenever I leave a tab open on MMO Champion I get a new tab opening on its own every now and then with adds like asian beauties, free online games, message to update my Firefox/Flash version (fake, but they look real). I never get this on any other website, and I scanned my PC with the programs mentioned below, it's clean.
I have the latest Firefox version, Avast AntiVirus, MalwareBytes with Website Blocking option turned on, Windows 7 with latest updates and Firewall/Windows Defender turned on.
Like today I went to eat breakfast and watch TV, I came back an hour later I had 6 new tabs up, all with random adds and update messages.
Sometimes when I look at my MMO Champion tabs they do the refresh animation as if something is refreshing them even though I'm not.