Found yer answer
BT (British Telecom)
(i assume too much)
Joking aside, hmmm
Looking at your memory, and OS, id have to say it could be the Modem drivers of your DSL modem, are you using a BT line but using lets say Orangeonline (or whatever they call it), or any other of those type of companies, not sure which they all are.
Im on Cable modem, with VirginMedia (formaly NTL) and havent had any probs.
i take it you are using a SpeedTouch DSL modem ? ( i could be wrong)
did you try the ipconfig /renew ?
also have you browsed the Resources CD ?
Microsoft have a habit of hiding vital stuffs