Airport vehicle traffic and CTD's

One thing I have never had with 2.5 or 3 or 3.1 is CTD's.  The other day I read about setting some airport vehicle traffic to enhance the look of P3D, and since I am getting pretty good FPS with the 737 NGX, I decided that I would give it a try on minimum. The next 5 VA flights that I flew, P3D v3.1 crashed each time. Three times right after landing and getting ready to taxi to the gate, and twice when getting ready to taxi to the runway. I switched the vehicle traffic back off since that is the only thing that I have changed, and seems stable now. Hopefully that is what is causing this problem.