I wondered why some file associations were broken and stumbled upon a nasty problem: I cannot access the key HKEY_CURRENT_USER\Software\Classes.


As you can see above, I cannot view its current permissions, nor its owner (which should by SYSTEM). And no matter what I tried I'm unable to fix it. Trying to change the owner gives me a permission denied (also when trying from the Administrator account). RegDacl, which seemed to help another user, also aborts with a permission denied error.

Any suggestions how to repair this? If I cannot repair this I guess I have to dump that user account and create a new one. Are there any "diff-like" tools out there to help copy over registry keys?

  • Did you open regedit as "run as administrator"? – Moab Dec 10 '10 at 22:26

You need to access the registry as SYSTEM. From an administrator command prompt, run:

psexec -s -i regedit

This gives you system level access to the registry keys and you can do ANYTHING. Be careful.


You can edit registry with Emergency Boot CD ( http://www.prime-expert.com/ebcd/ ) which ignores key security descriptors and allows access to everything. By copying key security descriptor from root key to HKEY_CURRENT_USER\Software\Classes you can reset its ACL to default.

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