Anybody who works will SharePoint will grumble if you mention DCOM activation permissions. No matter how hard we try, how many patches we install (or how hard we try to ignore it), granting activation and launch permissions to the SharePoint service accounts is like plugging a dike with water-soluble filler.
On Server 2008 R2 our job is made that much harder by the fact that, by default, even administrators can’t edit the security settings for the IIS WAMREG service (GUID {61738644-F196-11D0-9953-00C04FD919C1}, for when you see it in your application event log).
The fix is to change the default permissions on a registry key, which you can only do by taking ownership of the key. My only comment would be that those permissions were locked down for a good reason in Server 2008 R2 and it’s somewhat frustrating that we need to do this.
Anyway, the key you are looking for is:
HKEY\CLASSES\ROOT\AppID\{61738644-F196-11D0-9953-00C04FD919C1}
To change the ownership you need to click the Advanced button in the Permissions tab of the properties dialog, then select the Owner tab. I’d recommend changing the owner to the Administrators group rather than a specific user, and make sure the permissions for TrustedInstaller are the same after you finished as they were before you started.
Once done, you can edit the DCOM permissions for the IIS WAMREG service in the same way as on other versions of Server 2008.