I think you discovered something, -K-:
See attachement "permissions.jpg" for more details.
When I select the Key, it says that this key can not be opened. I can right-Click it and select permissions, though.
There are no permissions set. I can set them, but they are not saved, since Access is denied.
I downloaded the fix and applied it. The errormessage as seen in the attachement dialAFix.jpg shows up. I know that on an english OS this error Message reads
"An event was unable to invoke any of the subscribers".
I did what you asked, but on the new administrator account the same problem occurs. When I try to install the Windows Installer, it hangs with the very same error message as before. I am quite sure I have a lot of new updates, though. Until a month or two ago, I regularly downloaded new updates. The problem is fairly new, I think.