Troubleshooting desktop build receiving unhandled NULL exception

Hi,

I'm looking for some help troubleshooting an OSX desktop build of my game. The game plays fine within unity, and throws no errors to the console. When I build the program, it plays fine for about 2 or 3 minutes, then the image freezes (sound keeps playing). The system console displays the following two messages over and over again.

6/21/11 11:04:26 AM [0x0-0xb00b0].unity.Monadnock Media.Deep Explorer[3429] Receiving unhandled NULL exception 6/21/11 11:04:26 AM [0x0-0xb00b0].unity.Monadnock Media.Deep Explorer[3429] Trying to recover from null exception

and finally:

6/21/11 11:04:27 AM [0x0-0xb00b0].unity.Monadnock Media.Deep Explorer[3429] process 3429 exceeded 500 log message per second limit - remaining messages this second discarded

The freeze seems to happen randomly, and not when I'm going anywhere in particular, or doing any particular thing. Time till freeze varies, but usually happens 1 to 4 minutes from launch. I have tried both universal, and Intel only builds. I have tried the game on two different macs including the one it was built on. It still crashes. I can play indefinitely within unity, and not get a single message in the unity console. I have "Script Debugging" enabled in my publish settings, but I can't find any further logs than the repeating console message upon freezing. The message doesn't tell me anything about what is sending a NULL exception. Is there a more detailed crash log published somewhere?

Any other ideas on how I go about troubleshooting this?

Thanks,

-Matt