PMDG 747 Problem

Hello,

I've had the PMDG 747 for almost 2 years now and until few months ago it worked perfectly.

But now I have to experience the following problem:

At first the plane and the textures are perfectly fine, but several minutes after the departure, all the textures change to plain white, even the inside of the engines (in the wing view) turn white and you can only view the silhouette of the airplane. At this point the 2d panel and the virtual cockpit still work but after a few minutes fsx just stops working without any kind of error report.

This is really annoying, as I really don't know what could be the problem. 

When I fly the PMDG 777 (or other payware aircraft), everything works fine (textures, cockpit,...) and the fsx does'nt crash.

I use REX essential + OD, GEX Europe, FSPassengers and usually FlightBeam KSFO or other addon airports.

Thanks in advance for the help.

Greetings, Chris