Hi mgerics,
Not sure what would have caused the issue, but you could try booting to a Linux live CD, to take partially take the OS out of the equation. Of course you would have to find a Linux distro which supports your NIC 'out of the box'.
Other than that, did you make any other changes prior to this happening, such as installing software, or make any system settings changes? Did you install/remove/enable/disable any other hardware? Have you checked the device manager for issues? Have you checked System Information for conflicts? These are just a few things that came to mind...
Oliver
