If you installed the latest security patches manually or via WSUS, this included MS05-051. On systems where the default security on %windir%subscriptions has been modified, you may experience the following symptoms (from the KB article):
- The Windows Installer service may not start.
- The Windows Firewall Service may not start.
- The Network Connections folder is empty.
- The Windows Update Web site may incorrectly recommend that you change the Userdata persistence setting in Microsoft Internet Explorer.
- Active Server Pages (ASP) pages that are running on Microsoft Internet Information Services (IIS) return an “HTTP 500 – Internal Server Error” error message.
- The Microsoft COM+ EventSystem service will not start.
- COM+ applications will not start.
- The computers node in the Microsoft Component Services Microsoft Management Console (MMC) tree will not expand.
- Authenticated users cannot log on, and a blank screen appears after the users apply the October Security Updates.
The fix is to reset permissions per this article:
(Incidentally, we talk about this in today’s podcast, which will be available some time this weekend).