I actually have this problem myself, and have not figured it out yet.
what I did is get a new wireless card to connect to my router. it works, but I still haven't got it to connect using any wired NIC.
here's what I tried to do:
- downloading and run this Winsock
- reinstalling Windows (even a format)
- using a new NIC
- uninstalling and reinstalling it
- using different drivers
- manually assigning an IP
you're welcome to try any of those, although since they didn't work on my machine I don't think they'll work on yours