Regarding having to do a kill -9 on the Squeak VM and not knowing why.
Let me point out that on unix based systems it is easy to attach the  
debugger to a process/application then do real-time debugging. One of  
the things you can do is stop the interpreter and then call the C  
subroutine to print the stack so you can see what's up

[otter:~] johnmci% ps -ax | grep Squeak
  3944  ??  S      0:11.46  

/Users/johnmci/Documents/Squeak3.7.0/build/Squeak  
3.7.4Beta1b.app/Contents/MacOS/Squeak VM Opt -psn_0_4849
  3978 std  R+     0:00.00 grep Squeak

"Everything I need to identify the program path and the process id I  
need for GDB"

[otter:~] johnmci% gdb  
"/Users/johnmci/Documents/Squeak3.7.0/build/Squeak  
3.7.4Beta1b.app/Contents/MacOS/Squeak VM Opt" 3944