I have Brighthouse high speed cable, Mozilla Firefox, Windows Xp. Working fine until about two weeks back, started receiving "Server not Found" Firefox can't find server at www.example.com. Sometimes it connect sometimes not, using the same address. It's doing this on all my comps, yet they show very good connection. Have used Super-antispyware, Malwarebytes Anti-Malware and Systems Mechanics Professional and others, nothing helps. Any ideas?