Hi Folks,
I had initially no problems at all with freezing until I progressed to long haul flights. Then I encountered issues with every flight. I emailed PMDG and they replied quite promptly that, in their opinion, I was experiencing OOM issues and that the best course of action was to turn TRAFFIC and AUTOGEN settings down to the minimum and then gradually increase these settings until the problem (freezing) returns. I have followed this advice and although my settings are still quite low, The freezing problem has not reoccurred for four flights now.
I am not running an overclocked system and I don't have a lot of scenery installed at the moment.
If freezing reoccurs then I'll drop a note here.