I've run into this and I've determined that the crashes have been caused by the older 32-bit plug-ins (for example, the KJaerhus Compressor seems to cause my system to crash on the export.) I replaced it with the Sonitus Compressor and it doesn't crash. I'm in the process of cleaning up all my plug-ins and weeding out the problematic ones, but its not so easy to do. Every time Sonar crashes, I either have to reboot or kill the SONARPDR.EXE process which usually takes 5 minutes to die.