Integrated NIC vanished - SOS

Last night everything was fine.

This morning, I could not connect to the internet and my NIC was not listed under device manager.

I saw this as an opportunity to get the 64bit version of windows since it best fits my hardware. Did a clean install, the NIC is still not found.

It is enabled under bios.

Cannot reinstall drivers because it claims the NIC was not found.

Does not work in safe mode either.

My motherboard is an Asus M4A785-M. The NIC has an orange and green light on constantly (solid - NOT blinking).

Any ideas?

That was very strange.

As I went to put a new NIC card in (from older pc)...

I noticed that the two lits stayed on even when the PC was powered off.

I killed power completely for 10 seconds, turned the PSU back on, powered the PC back on - now the NIC is recognized and works just fine.

I'm still curious as to what might have caused this?