McAfee Addins throw a wobbly

Here is a nice error thrown up by Mcafee today. Doing a staged upgrade of our old VirusScan software to the latest 8.5.0 enterprise version all appeared to be going well however on reboot several of our users were getting the following error:

Having logged on as myself I was not seeing this error. The extend.dat file is basically a copy of some registry settings that are put there to speed things up when opening Outlook. Upgrading over the network had done everything right in the registry but Outlook keeps going back to this file instead of copying the registry settings to a new one.

In the end an easy fix, delete the extend.dat in the path given in the error and Outlook recreates it the next time it is launched. Microsoft knowledgebase covers it here: http://support.microsoft.com/kb/204951