Importing package on Windows XP

[M.-H. Z]

Dear Dave,
You are absolutely right!
I changed my code so many times that I got confused when writing the
post.
Actually, I tried "from mod import module1" and "import mod.module1".
Of course, they led to the same error: the one that Peter pointed.
Anyway, thanks a lot for your help!
Matthias.
(Yet, I did not find the mistake in my project... But I still cannot
precisely locate it from whole lot of modules that I use.)