When uninstalling Symantec Antivirus, you can sometimes be left with the following error each time you start Microsoft Outlook:

The add-in Symantec Antivirus..   vpmsece3.dll cannot be downloaded and has been disabled by outlook.

Symantec has a fix for this problem which is available here:

Download Symantec Plugin Util

Run this application, and when you’re prompted if you want to delete extend.dat, select yes.