I just purchased and installed the 747 QoTS II v3 and I'm already having issues. P3dv4 loaded fine the first time with the Delta 747-400, but since freezing my pc, I haven't been able to get the 747 to properly load in the selection screen and then it won't start the scenario. It just freezes up with the little load circle spinning and then eventually give the "Prepar3d stopped responding"

Something must be on your end as PMDG747 is butter smooth and trouble free addon.

I suggest to open support ticket on PMDG web site, they are very quick and helpful.