Registry Permission Errors

So, I was trying to install Windows XP Service Pack 3 tonight, but I ran into some issues. I kept getting errors that it couldn't backup a few registry keys. I'd seen something similar to this when I ran programs like Adaware and Spybot Search & Destroy. They'd hit a certain registry key and give various errors about not being able to access it ("access denied", "failed to open...", etc.).

Manually editing the registry was even more strange. I could find the registry keys in question, but it appears that there were no permissions set on the keys. Therefore, as soon as I'd click on keys like HKEY_LOCAL_MACHINE\SOFTWARE\Classes\IMsiServer\CLSID or HKEY_CLASSES_ROOT\.msi, and HKEY_CLASSES_ROOT\.raw, I'd get a popup with the error "Cannot open .msi: Error while opening key." Something like this:



Well, after some long hard searching, I found a solution! With these simple steps, I've been able to restore permissions to these keys with minimal fuss.

1. Find the key in Regedit

If you've forgotten, it's Start > Run > type regedit and hit enter > browse to the key in question, or do an Edit > Find for the key name. You'll know you hit it when you get an error dialog box like the one shown above.

2. Set a key owner

This wasn't so obvious. First, close out of and ignore any errors you get during this process (you should only see two - and you've already seen one of them). Now, do the following:

• Right-click and select Permissions

• Click the Advanced button
• Chose the Owner tab

• Selct the Administrator's group in the "Change owner to" list
• Click OK to assign the Local computer Administrators group as the owner
  
• Back on the Permissions tab, click the Add... button
  
• In the Select Users or Groups tab, type administrators in the box and click the Check Names button (it should fill out the details of your administrator user information; if not, try using the Advanced button to find it)

• Click OK to add the Administrators group to the Security list
• Check "Full Control" and "Read" to give the Administrators group full permissions
  
• Click OK

3. You should be done!

Close out of the registry editor and try whatever you were doing again (installing a service pack, application, etc.). If you get another error, it may just be on another key. Repeat as necessary.

Hopefully that helps you fix some of the very frustrating registry problems that key permissions can cause!