Having removed Internet Explorer 8 from a Citrix Presentation Server farm, the following errors started appearing in the Application Log:

IE8 uninstall errors in App. Log (1)

It shows up with 2 different messages, but with the same event ID:

IE8 uninstall errors in App. Log (2)

.. and

IE8 uninstall errors in App. Log (3)

This happens because IE8 doesn’t remove all traces when it uninstalls. There’s 2 leftover (empty) keys in the registry, and the errors then appear everytime a user is accessing IE7.

The keys to delete are:

7B849a69-220F-451E-B3FE-2CB811AF94AE

CF7639F3-ABA2-41DB-97F2-81E2C5DBFC5D

And they are both found in:

HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\GPExtensions\

Apparently this error has been present since IE8 beta, and it still hasn’t been fixed by Microsoft. Shame on you.

No restart needed.