I have been having the same problem for ten days now - it started when i was on bear share i have all kinds of problems since . I contacted telewest who told me it was basically my fault.
i have got really fed up of constantly pulling the power lead out of the webstar modem .
I had a look on the
http://192.168.100.1
it gave me some very interesting information from my modems log
i had BPI flash : The mfg CA Cert not found
DHCP warning - non critical field invalid in response
msn messenger tells me my default gateway is offline
can any one help - telewest are insisting it is me