Seems this RealTek LAN adapter/chip is a REAL problem on these motherboards!
Once again, it stopped working. No reason, it just stopped.
For a while, I was able to get it working by running the RealTek diagnostics, but this time, no go.
So, I stuck in a 1GB network card and began using it.
Then yesterday, I was at the GB site and noticed they have upated their LAN driver -- again.
So, I downloaded that, replaced the older driver with the new one -- and the onboard LAN works again!
This is the second update of this LAN driver in a few months. They must be having serious problems with it.