[Zope] external process

Hi all, I can't seem to get Zope to initiate an external process. I've tried to use External Methods and the Python os library functions spawnv() and fork() with execv()/system(). In each case the functions run and return but nothing else happens. Running the same function calls from Python outside of Zope works fine. Anyone have any ideas why it wont work or how to get it to work? Micah