me too having this problem. i was requesting deboarding after arrival at gate. P3D v3.1 PMDG 777 (latest version)
It seems you have TWO problems at the same time:
1) The "RuntimeError: cruise speed must be positive" error has been discussed many times on the forum, and it an error of the scenery. It indicates the scenery AFCAD has an error, like overlapping nodes, orphaned nodes, unconnected links, unreachable parkings, etc. You might try to fix it using the ADE or AFX "Fault Finder" options, or at least having an idea what's wrong with the AFCAD, and report it to the developers.
2) The UNRECOGNIZED_ID errors it's something we never be able to trace, but in one case they were found to be related to have the VRS Tac Pack installed and went away by removing it:
http://www.fsdreamteam.com/forum/index.php/topic,12542.0.htmlNote that, we have been in contact with VRS, they sent me their module to try, and I was never able to reproduce the problem...