Error: Symantec Antivirus Outlook Addin gives error when opening Outlook

When you start Microsoft Outlook, you receive an error message.

"The add-in 'C:\Program Files\Symantec_Antivirus \vpmsece4.dll' could not be installed or loaded."
This problem may be resolved by using the "Detect and Repair" in the Help menu.
Unable to load "C:\Program Files\Symantec AntiVirus\vpmsece4.dll".
You may be out of memory, out of system resources, or missing a .dll file.
The error message may reference the file "vpmsece3.dll" or "vpmsece4.dll."
Use of the "Detect and Repair" option, as suggested in the error message, does not solve the problem.

The Outlook email plug-in for Symantec AntiVirus 10.x is not removed from Outlook after migration to Symantec Endpoint Protection 11.0.


Before you begin: If you see "NavNT" in the error message instead of "Symantec_Client_Security", or you use Symantec AntiVirus 8.x or earlier, instead read the following document:
Error: "The add-in 'C:\Program Files\NavNT\vpmsece.dll' could not be installed or loaded …"
To fix the problem, navigate to Add-in Manager in Microsoft Outlook and uncheck Symantec AntiVirus 10.
In Microsoft Office 2003, the Add-in Manager can be found in:
Tools> Options… select the Other tab then Advanced Options… Then Add-In Manager…

In Outlook 2007 the Add-ins is located in the Trust Center:
Tools> Trust Center…, then select the Add-in on the left side.
Then check in the drop down box at the bottom called "Manage". Go through all 3 choices, Com add-ins, Exchange client add-ins and Disable add-ins.
If that does not fix the problem, find and delete all copies of the "Extend.dat" file on the computer. A copy of this file exists for each local user account. Then, restart the computer.
Note: You cannot delete copies of the "Extend.dat" file for other user accounts unless you log on with an account that has local administrator rights.

To find and delete copies of Extend.dat
Close "Outlook" if the program is open.
Confirm that Windows is set to "show hidden and system folders."
To show hidden and system folders, read How to make Windows show all files.
On the Windows taskbar, click Start > Search > For Files or Folders.
Under "Search for files or folders named," type the following text:


Click Search Now. Wait for the search to finish.
Delete all copies of the "Extend.dat" file.
Restart the computer.

If a Group Policy that hides system files is in effect, you may not find the "Extend.dat" file when you search or browse, even though you have set Windows to "show all files." If you do not find any copies of the "Extend.dat" file, use a command prompt to delete the file(s).

To find and delete copies of Extend.dat from a command prompt
Close "Outlook" if the program is open.
Click Start> Run.
In the Open box, type cmd
Click OK.
At the command prompt type the following command and then press Enter:

cd "C:\Documents and Settings\<local_user>\Local Settings\Application Data\Microsoft\outlook"

Where <local_user> is the name of the current local user.

Type del extend.dat and then press Enter.
Delete the "Extend.dat" file for every user local account on the computer.
Restart the computer.

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