How-To: Fix Trend Micro Add-In Missing in Microsoft Outlook

This post will be the first of many that I plan to write that detail some bugs, technical issues, and problems I’ve had to fix in some way.
I had a friend come to me with an issue: Every time they started up Outlook, they received an error saying that the Trend Micro add-in was missing. Reinstalling Trend Micro did not correct this issue. I thought this was going to be an easy fix. I started by trying to disable the plugin via the Tools/Options area of Outlook. Unfortunately, there was no listing for anything from Trend Micro. Yet, Outlook seemed to think there was something.
One solution I found online was to delete the extend.dat file that Outlook uses to know which extensions are installed. On Windows XP, that is found at:
C:\Documents and Settings\%username%\Local Settings\Application Data\Microsoft\Outlook\
On Windows Vista and Windows 7:
C:\Users\%username%\AppData\Local\Microsoft\Outlook\
Once this file was deleted, I reopened Outlook. Outlook rebuilt the file, and we never saw an issue with a ghost Trend Micro plugin again.
Did you find this solution helpful? Or did you find another solution to this problem? Leave a comment!