Hi notrom, and welcome to Cable Forum

(ooooo never done that before!!!)
My guess would be that you have IE set to automatically configure it's settings:
Goto Tools -> Internet Options -> Connections -> Lan Settings
You should see an
Automatic Configuration section.
If either
Automatically detect settings or
Use automatic configuration script are ticked, try unticking them so they are not used.
These settings are usually for use on a LAN, and as far as I know, are not set by NTL software, well wasn't on my PC.
Cheers
MikeyB