I don't know whether this is relevant, but I frequently used to loose my ADSL connection. It was impossible to say what caused it. Sometimes it would work for hours then stop, sometimes it could fail twice in five minutes. In all cases, connection could be restored by disconecting the modem/radio LAN from the mains supply and reconnecting so re-initialising the connection. Extensive virus checks came up squeaky clean, but before blaming a faulty modem or worse I tried Spybot. Bingo! I am pretty sure that the culprit was the Ebay toolbar that my wife found so useful on her machine!
P.P.