ESET Outlook Plugin error when starting Microsoft Outlook

If you receive the following error message when starting Microsoft Outlook,

The Add-in 'ESET Outlook Plugin' (C:\PROGRA~\1ESET\ESETNO~\1EPLGOU~1.DLL) cannot be loaded and has been disabled by Outlook. If no update is available, please uninstall the Add-in.

please see the information contained in this article.

The error message above may occur on a computer with multiple user profiles after an upgrade, reinstall, or failed uninstall of ESET Smart Security.

Solution 1: Outlook 2003 and 2007 - Delete the extend.dat file

The extend.dat file contains cache for add-ins in Microsoft Outlook which are activated by the Add-in manager. If you delete the extend.dat file and restart Outlook, a new .dat file is automatically created. The new extend.dat file should contain no inconsistencies and should prevent the error from occurring in the future.



To delete the extend.dat file (Windows XP):

1. Exit Outlook.
2. Click Start - Search - All files and Folders - More advanced options and select the Search hidden files and folders check box.
3. In the top search field type extend.dat and click Search.
4. In the search results section, right-click on the extend.dat file and click Delete.

NOTE: If Outlook is used by multiple profiles, an extend.dat file exists for each profile. Each extend.dat file must be deleted. By default this file is located in C:\Documents and Settings\Username\Local Settings\Application Data\Microsoft\Outlook.

To delete the extend.dat file (Windows Vista):

1. Exit Outlook.
2. Click Start and then click Search. Click Advanced Search in the upper right corner.
3. Select the Include non-indexed, hidden, and system files (might be slow) check box on the left. On the right, type extend.dat in the Name field and click the Search button.
4. In the search results section, right-click on the extend.dat file and click Delete.

NOTE: If Outlook is used by multiple profiles, an extend.dat file exists for each profile. Each extend.dat file must be deleted. By default this file is located in C:\Users\Username\AppData\Local\Microsoft

Solution 2: Install Office 2003 Service Pack 3, or other available updates

If you are using Microsoft Outlook 2003, you can install Office 2003 Service Pack 3 to resolve the error message. That, and other updates can be installed from here:

http://office.microsoft.com/officeupdate/