Hi
I'm running out of ideas here but you could try uninstalling your network card in Device Manager and then rebooting your computer.
This should force Widows to re-detect your card and re-install and reconfigure the drivers for it.
If this doesn't work I don't have any idea what could be going on.
One of the things that has really gotten easier is getting your connection set up, it is pretty much the first thing that Windows does anymore, with no input from the user by the time that Windows opens the first time it has already gotten online and downloaded updates.
I know that Bonjour Services can cause problems in Windows 7 connections, you might look and see if that is installed.
It is installed along with ITunes and some Adobe software.
Also, try booting in Safe Mode with Networking and see if you have a connection.
If something is conflicting that might show it.
Maybe someone else has some other ideas.
Mike