When attempting to install Exchange 2007 sp2 on a server I was getting the error message Could not open Key UNKNOWN\Components\ 32 hex numbers \ another 32 hex numbers (see below)

This turned out to be occurring when the Rollup 9 package was being uninstalled. Checking into the registry and hklm \software \ microsoft \ windows \ CurrentVersion \ Installer \ UserData \ S-1-5-18 \ Components \ numbers \ numbers. Taking ownership of the parent registry key and then assigning my admin user full rights to the parent and cascading permissions would allow the procedure to continue a little bit further. Eventually after a couple of attempts I expanded the Components key in regedit using ctrl + and then used the arrow key to move all the way through, fixing permissions as required.  The lazy way would have been to set permissions at the Components Key but that may cause other problems I didn’t really want to deal with in the future.

I have no idea why the permissions were so screwed up but I really do not appreciate wasting 4 hours on a Saturday afternoon trying to fix the issue – it took a while to debug the initial errors and then more time to run the install, find out it kept causing errors with different registry locations and then navigate through the entire component tree.