Mikeybrass,
Your problem sounds strangely similar to mine that I posted here:
http://www.cableforum.co.uk/board/sh...3&goto=newpost
I thought that the Linksys router had a problem, but have since found that it's actually the cable between the cable modem and the router. If my pc is connected directly to the NTL 250 using the same cable, I can gain an IP address and access the internet. If I then put the Linksys router on the same cable, I can't get an IP address.
Now here's the strange part, if I substitute a spare 2m CAT5 cable, the Linksys router works fine, so I know that its a cable issue in my case. Either the cable (10M) is too long and the losses are too great or there's a compatibility problem. My existing cable was not CAT5, so the next thing that I'm going to try is substituting a 10M CAT5 cable and if that doesn't work, I'll buy a shielded CAT5 cable.
Hope this helps.