I like the idea of resetting the BIOS. Go into your BIOS settings and go to the EXIT tab and choose "Reset BIOS Defaults", or similar language.
Two other possible solutions you could try:
1- run a Repair Install to try and correct the driver errors. Something smells like the guy you dropped this thing off to played the computer version of "52 card pick-up". A Repair install may set this right: Repair Install
. Be sure to read all those warnings in that Tutorial.
2- Update the video cards firmware (Video card BIOS): HOWTO: nVidia BIOS Flashing - Overclock.net - Overclocking.net
. That may correct why the card is not recognized and being seen as a Ethernet Controller - which is the actual cause of your issue - but the issue is "Why?".
Which one of these you try first is up to you. I might try the firmware update first myself.
And we can't overlook the possibility that the video card is no good. That would also explain it.