The browser or Windows network service could be hijacked, too. No matter what link you click on, the hijacking malware always redirects you through another server, and Avast can detect the malicious redirect, where you, the user, would never actually see any change in your browser's behavior, but any decent internet security software will. So also make sure your computer is free of browser hijackers and trojans. May need to run other freeware scans to be thorough, like Malwarebytes' Anti-Malware. Avast is great at preventing infection, but if malware does manage to infect your PC, Avast has never been able to reliably remove the whole problem in my experience. Worst case, consult bleepingcomputer.com for the most effective malware support...for free.