I noticed on my past 2 flights with the 744, that when I clicked on the PFD to bring up the pop up, the game would freeze, then crash. No error message, and nothing logged in event viewer. On today's flight, I popped up the FNC just fine not long before the PFD. And both times it was about 7-8 hours into the flight, so maybe it's a memory issue? Because it works fine in the beginning of the flight. It's on P3Dv3, Win10

Using the left PFD 2D popup is a known problem that goes back to the release of P3Dv3.0.  We recently tested it without any PMDG code, using only SDK xml and the sucker still crashes.  LM says it's not their problem.  This is where things rest for now.  Simple solution, don't use the PFD popup.  The FO PFD is available and has not been shown to cause the same problems.