Saw this for the first time; on a Windows 7 laptop, all network devices except two, were yellow-flagged, and in their properties it said code 31, which means not able to load the driver files. In this condition, I found that I could not uninstall any network objects in Device Manager: it permitted me to do so, but immediately after the deletion was done, the objects remained.

I googled it a lot, found zero of real use, except the underlying pattern that apparently one very badly-behaved network driver or virtual device, can hose the whole Windows 7 networking stack in this very way.

In this case, there was a certain high-profile vendor’s VPN client installed, and it was this vendor’s items which were not yellow-flagged, but instead, were marked disabled. So I focussed on that, deleted the .sys file involved, and deleted every registry entry for them also, in safe mode, excepting only the LEGACY entries which I could not get permission to delete, even running regedit as administrator. No change: the objects remained after reboot.

I then tried System Restore, and took the OS back to the point before the issue began to occur. This had a very positive result; networking came back. The VPN client will need reinstalling, but I will update the machine all the way as next step, and then install the latest version of the VPN client.