OK, so about an hour (yeah, yeah; I know .. I shouldn’t be working at that time, but it really gave me sleepless nights) ago, I finally figured out why the hell both my Windows XP Embedded thin clients as well as my Windows Server 2003 systems where showing this real weird behaviour when applying group policies, or more precise the user based configuration of a group policy.
The inspiration came to me after reading this and taking a look at regedit myself, where I noticed the entry " Permissions" for the first time ever since I’m using regedit. I also noticed, that the regedit permissions seem to be using the same groups, one would assign to NTFS resources.
That said, it really all boils down to the ntuser.dat (which IS HKEY_CURRENT_USER). As I created the profile with a different user than I am using it with (basically, I want ~12.000 users to use this one profile), I needed to change the permissions INSIDE regedit to include a group containing all these users. After that, any user could again merge the settings from ntuser.pol into HKEY_CURRENT_USERSoftwarePolicies, which in return gives you the joy of your fucking policies working again.
TADAAAAAA! About two weeks worth of work spent for such a shitty thing, and noticing it when you’re off work – priceless!