How to fix the “Could not connect to Group Policy Client service” Error

Recently a few of our Windows Vista machines have experienced a problem after removing Script Logic Desktop Authority from them, causing non-admin users to not be able to log into the machine.

GP-Client-service-error-large

The message that appears is
“Could not connect to Group Policy Client service. Please consult your system administrator.”
but strangely sometimes manifests as
“Windows could not connect to the system event notification service . Please consult your system administrator.”

After seeing this message, a normal user is dropped back to the Ctrl-Alt-Del logon screen.

This is how you can solve the problem if you are experiencing a similar problem

1. Log on to the machine as administrator
2. click start and into the search box type “Event Viewer” and press enter
3. Look in the Windows Logs under System for any Warnings or Errors. The error message will be something like Windows cannot process Group Policy Client Side Extension (Daci). Exception (in my case it was daci which is part of the script logic desktop authority program)
4. On the details tab, take a note of the GUID for the faulty client side extension
5. click start and into the search box type “regedit” and press enter
6. Navigate to HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\GPExtensions and then click on the string that represents your faulty GP Extension.
7. click on the file menu and choose export and save a backup of the file.
8. Once the registry is backed up you can delete the folder that corresponds to the GUID
9. Do a restart and log on as a normal user.

Problem solved!