I had exactly the same problem about 18 months ago. It turned out that it
was zonealarm. I did exactly as you did and stopped it from loading at startup, I still got the same problem - this is because there are still some elements of ZA that
will load even if you have told them not to.
You need to do one of two things:
- Completely uninstall ZA (I'll find the instructions for total removal of ZA for you shortly), or
- You need to configure ZA so that it sees your Cable Modem as a trusted part of the network.
What's happening is that ZA is interefering with the DHCP lease process, I think it's not allowing the requests which go between PC and Modem to be actioned properly.
Like I say, give me a moment and I'll see if I can find the instructions for how to take care of the two points above for you.