Hi Hidden Hippo , This may not be what you wabnt to hear, but I had very similar problems with my Z68AP-D3. I spent several weeks (on and off!) trying to resolve this with all the good help from this forum, but did not succeed. End result - I RMA'd the board , got replacement within 8 days, loaded drivers from CD and ethernet worked first time.
Suggest you try solutions posted here, but don't spend weeks trying to fix it - boards do slip through with faults - get it RMA'd it worked for me.
Best of luck with this Allanm