[mod_python] Python Debugger doesn't start in Mod_Python

Since my small intranet application keeps getting more complex I tried 
to fix some bugs using the Python Debugger. According to the Mod_python 
manual I added the "PythonEnablePdb On" directive into the directory 
context of my Python application and started httpd from the command line 
with the option -DONE_PROCESS (after stopping httpd first, of course). 
But Apache didn't start and an error window occurred instead showing the 
following message:

"Runtime Error! Program: <Apache path>\httpd.exe. This application has 
requested the Runtime to terminate it in an unusual way. Please contact 
the applications's support team for more information".

I'm using the following prebuilt binaries on Win2k SP4:

mod_python-3.3.1.win32-py2.5-Apache2.2.exe
python-2.5.msi
apache_2.2.4-win32-x86-no_ssl.msi

When Apache is started with the option -DONE_PROCESS but without 
Mod_python there is no error and no Mod_python either (of course). On a 
different machine with WinXP SP2, Apache 2.2.3, Python 2.4.3 and 
Mod_python 2.7.10 the debugger works as expected.

Does anyone have an idea how to fix this?

Thanks

René