Crash on MIDI import

Hi

I'm a new user - just starting out with MS. I have a piece of music (an arrangement of Chatanooga Choo Choo) that I created with Acoustica Mixcraft and then exported to MIDI but when I import it to MuseScore it crashes every time - see attached. I am using Win 7 Home 64 bit - I have tried using a different OS (Vista 32 bit) but the problem remains.

The details are

Problem signature:
Problem Event Name: APPCRASH
Application Name: mscore.exe
Application Version: 0.0.0.0
Application Timestamp: 512df23e
Fault Module Name: mscore.exe
Fault Module Version: 0.0.0.0
Fault Module Timestamp: 512df23e
Exception Code: c0000005
Exception Offset: 00113dd3
OS Version: 6.1.7601.2.1.0.768.3
Locale ID: 2057
Additional Information 1: 0a9e
Additional Information 2: 0a9e372d3b4ad19135b953a78882e789
Additional Information 3: 0a9e
Additional Information 4: 0a9e372d3b4ad19135b953a78882e789

Thanks for your help