thx for answer, but using regedt32 to set permissions for everyone is exactly what i didn't want to do :-(
Key i am trying to set is
HKCU\SoftWare\Microsoft\Windows\CurrentVersion\Policies\Explorer Value NoDrives.
Security on HKCU\...\Explorer is SYSTEM and Admins Full Control, the owner has read access.

thx in adv,

Luuk