Spawning a new process from Python

[Jan Dries]

I'm trying to start a process from within a Python script. The process 
is a commercial application (ASP server) written in Java. This ASP 
server tends to hang from time to time, and my Python scripts tries to 
detect that, kills all ASP child processes, and then starts the server 
again. It starts as root (to kill the processes) and then switches to 
used nobody (with os.setuid()) to start the ASP server again.
I can kill the server properly, but can't get it running again. At the 
command prompt, I normally start it with:

/path/to/start-server.sh &

which is a script that actually starts the Java VM with some parameters.

I've tried various things in Python:
os.system("/path/to/start-server.sh &")
os.spawnv(os.P_NOWAIT,...)
os.spawnv(os.P_WAIT,...)
os.execl(...)
os.execve(...)
...

With some of these instructions I can manage to seemingly get the ASP 
server running, but once the web server tries to connect to it, it gives 
an internal server error.

Does anybody have any idea what I might be doing wrong?
I'm using Python 2.1.3 on Debian Linux.

Regards,
Jan