RunningMan:Talkiet: Update - the crazy option I thought of has been checked and wasn't involved.
Personally, I think it was Solar Flares (*)
* - No I don't think that really.
Right, on a more serious note, given that has been ruled out, I'd suggest right back to basics for troubleshooting.
1) Turn off your modem, router, switch and computer.
2) PLug the computer directly in to the modem (unplug it from the switch, and plug that cable straight in to the modem.
3) Turn the modem on, and wait several minutes for it to start up and log on properly.
4) Turn your computer back on.
THEN, check what IP address, router and DNS the computer is picking up - you don't have to post the whole address here if you don't want to, but tell us if it is an external addess, internal (192.168.x.x) or self assigned (169.x.x.x).
ok I'll try this before the factory reset. hang on....
(got my tin foil hat on though ;) )