strange ntdll.dll errors

All of a sudden, MCE (Multi Crew Experience) has a tendency to crash during loading. It started yesterday, and 8 out of 10 times it crashes to the desktp, giving this error message:Problem signature: Problem Event Name: APPCRASH Application Name: mce.exe Application Version: 1.7.4.0 Application Timestamp: 4acce63e Fault Module Name: ntdll.dll Fault Module Version: 6.0.6002.18005 Fault Module Timestamp: 49e03824 Exception Code: c0000005 Exception Offset: 0002ac0f OS Version: 6.0.6002.2.2.0.256.1 Locale ID: 3079 Additional Information 1: 201a Additional Information 2: ba5fde5dd4303ab20ef6dec9a3a8d90d Additional Information 3: 4c9b Additional Information 4: 355b8788fb296This is with Vista 64, 8GB RAM, mildily overclocked Q9550 (to 3.2GHZ). Everything else is very stable, from time to time FSX refuses to start because of the RealityXP 530 gauge, but this is very rare (all suggested settings used).Funny enough, I CAN start MCE with a modified stock Cessna (other gauges), but not always - and as soon as I switch to another plane: Boom.Any idea what this could be?