ntl techs can see that the modem is online, even without it being connected to your PC, because it is a seperate piece of hardware, with its own unique address. If this address is registered on your local server (known as a UBR or CMTS), then the modem can be found and it will report as online/offline/ranging/whatever. In the case that it is online (as suggested by the ntl tech and by the fact that the SYNC and RDY lights are solid), it is most likely to be a problem with your PC. It is possible that the local DHCP server has run out of pre-registration IP addresses, but it is unlikely that the problem would have lasted this long.
You say that you are getting a 169.254.x.x IP address both through Ethernet and USB. This means, as you say, that it is unlikely to be a problem with your Ethernet card, and means it is almost certainly an Operating System issue. If you open a command prompt window (Click on Start, then Run, and enter
cmd, then click OK) and enter
ipconfig /release followed by
ipconfig /renew, you should get one of two messages:
- Unable to contact DHCP server, or
- An operation was attempted on something that is not a socket
The first means that for some reason, your PC cannot communicate with the DHCP server. This could be a corruption in the Windows network stack - try typing into the command prompt window
netsh int ip reset reset.log, then reboot the PC and see if you have an IP address then. If not, then some more detailed jiggery-pokery might be required to get your network connection working again. Alternatively, it's not impossible that the Cable Modem could be faulty - but it's unlikey to be online if that's the case. You could try getting ntl to replace it, but be aware that if they test the modem (at your premises, not remotely) and find that it is not at fault, you are liable to pay a call-out charge which could be up to £100 in some areas.
The second error means that there is
definately a corruption in your Windows Network Stack, and you will need to reset this to be able to connect to the Internet. This is very often caused by uninstalling Internet/networking software incorrectly. Have you ever had a firewall (especially McAfee) on this PC, and perhaps removed it? That can be a common cause of this particular error. More information on that particular issue, and how to fix it,
can be found at the Microsoft Support site. Be aware, however, that this does not always fix the problem, because it depends on exactly what is at the root of it.
Hope this helps!
Jimbo.