When I go to tweak the aircraft settings, specifically under the "failures" Tab in the FMC, the display shows "N6066 Aircraft" although the registration is C-FNNH (the Air Canada livery from the downloader). Does anyone else have mismatching FMC registration and aircraft registration?

I had a similar issue in the NGX. Check under CDU>PMDG Setup>Aircraft and see if the tail number at the top matches the plane you are in. If it doesn't, here's what Ryan told me to do with the NGX to fix it (I presume the same should work for the 777, at the very least it won't break it any more)

 

First, exit FSX. Then delete both PMDG 777 folders at this location: C:Users\(Your Windows Username)\AppData\Roaming\Microsoft\FSX\SimObjects  (you can also search %appdata% in the start menu on Windows 7, this will take you to the Roaming folder)

 

Re-start FSX, load the plane and check the CDU again as above. See if it has the right tail number and options.

That solved it! Thanks!!