FSX crash after 747x TCAS warning

My PMDG 747x works fine in FSX most of the time and I have enjoyed many long-haul flights with it already. But I have experienced FSX crash twice during the flights when I reacted to the traffic warnings that 747x TCAS system gave me. The first time happened few weeks ago when TCAS told me to lower the altitude and I did so by disengage the autopilot and push foward the yoke, then FSX suddenly stoped with an APPCRASH. The second time happened this morning when I followed the TCAS instruction to climb and FSX crashed immediately with the same APPCRUSH report:Problem signatureProblem Event Name: APPCRASHApplication Name: fsx.exeApplication Version: 10.0.61637.0Application Timestamp: 46fadb14Fault Module Name: API.DLLFault Module Version: 10.0.61637.0Fault Module Timestamp: 46fadb58Exception Code: c0000005Exception Offset: 000176f6OS Version: 6.0.6000.2.0.0.256.1Locale ID: 3081This problem ONLY occur to me when 1) TCAS system give me traffic warning and instruct me to lower or increase altitude and 2) I react to TCAS instruction by disengage autopilot then taking appropriate step. Otherwise 747x works perfectly fine on all circumstances.I am using 32-bit Vista and I have already resolved the FSX OOM problem by using the 3GB enabler: [http://files.filefront.com/3GB+enabler2zip/;6791818;/fileinfo.html] so I suspect its due to other corrupted scenery file or add-on but I am not absolutely sure about this.Has anyone here experienced similar problem like this?Regards,Junius