Andrew has been helping me out privately via e-mail on this matter, and when reading your comments here and connecting them up to my other friend's expericnes I understand that this is a known issue with no solution just yet.
There might be two causes here:
P3D v4.2 OR/AND PMDG 747 itself.
How did I come to this conslusion? Via elimination:
1. I tried installing LINDA 220.127.116.115 with a clean installation with no module installed - P3D crashed when loading the 747 on a new scenario.
2. I even tried installing my back up 2.9.3 from the P3D v3.4 days when it worked pefectly - did not work with P3D v4.2 - crashes when loading a new scenario.
3. Investigation with friends using LINDA, PMDG 747 and P3D 4.2 combination - who told me explicitly that they also suffer from his problem, and the only current solution for this is first loading up a scenario with a default aicraft (e.g. F-22) and only then switching to the PMDG 747 (as mentioned in the 2nd comment).
4. This I havent tried yet, that might worth a try: To check out if the problem exists with P3D v4.1 - I heard from friend its all OK there (not including jordanal's comment here on the 777).
Just a note here, probably mentioned earlier: The problem did not occur when loading up a new scenario with a PMDG 737 or a 777 - only with the 747.
Therefore, after doing all the checkings there might be a compatability issue with either PMDG 747 (who will obviously not support LINDA hence not release any suitable updates), or P3D v4.2 that might cause the problem. Maybe some FSUIPC modifications are required to solve this problem. I'm still no expert in these levels.