No response from LW GUI on Mac OS X

Hi,

I am using LispWorks Professional 5.1.1 on Mac OS X 10.5, to develop  
an application with a GUI.
I start my app from a LW Editor or from a Listener.
If my code is stuck in an endless loop, the LW environment gets non- 
responsive and I have to restart (kill from Finder) the whole LW  
environment.
I have learned that when starting my app from an Editor, it is run in  
one of the "Background Execute" threads, but since the LW GUI gets  
non-responsive I cannot go to the Process Browser to kill any  
process. The only thing I can do is move between the LW windows, but  
I cannot input anything.
Ctrl-G does not help either.

Does anyone else have the same problem?
Any suggestions?

A related thing I have noticed is that sometimes I get a Mac OS X  
Terminal window with the LW debugger, where I can backtrace or  
continue. Why do I sometimes fall into the Mac OS X Terminal instead  
of the normal LW debugger?

Thanks!
/Sven