We follow many of the "Standard" lockdown procedures suggested NIST and others. We have had a major problem after applying the MS05-051 patch. The problem that we are seeing is that all the network connections including pptp connection dissapear. If you try to recreate them it tells you that it can't because they already exists. Your networking still works but it cannot display the connections. We have tracked it down to a permissions issue in the windows/winnt directory. The fix for us was to add the network service account with read permissions on the %systemroot%\registration directory. The vanilla build permissions is everyone read permissions.

We would like to know if anyone else has seen this. Also I wanted to let you all know so you can be aware of the issue.