spawnl issues with Win 7 access rights

[Propad]

Hello everybody,
I have some trouble with a program I run both on a WinXP and on Win 7.
It boils down to this several lines:

import os
vePath = r'C:\Programme\RA Consulting_Webservices\DiagRA-MCD
\DiagRA_D.exe'
#vePath = r'C:\Windows\notepad.exe'
process_id = os.spawnl(os.P_NOWAIT, vePath)

Under Win XP they  open DiagRA just fine; under Win 7 I'm getting:
OSError: [Errno 22] Invalid argument
Needless to say, I checked the path under Win 7; it is correct.

As you can see, I tried the same lines with notepad, just in case;
same result. Works fine under XP, IOError under Win 7.

So I'm pretty sure it's some kind of Win 7 access rights issue... Can
anybody point me to a concise overview of the issues involved, and
maybe even the known solutions? Again, it's os.spawnl in Python 2.2,
under Win 7.

Thank you very much in advance.

Cheers,

Nenad