I got an error opening my MSoutlook 2007. There where suggestions over the web on how to remove this error message regarding the OUTLOOK Plugin but this one works for MS Outlook 2007 only. For the 2003, You just need to remove your extend.dat file. You can do this by typing in the RUN command, %appdata%, this will open a folder of the current application data that a user is login. Look for Microsoft folder and inside that folder look for OUTLOOK. Delete the Extend.dat file and it will work like a charm.
With regards to removing non-existing plugins on Outlook. Here is the step by step procedure on how you can remove the error.
On Tools menu. Click on the Trust center. as shown below.
Inside the trust center, Click on the Left tab ADD-INs.
Search for the Plugins that you are having an error. On the screenshot are the COM add-ins. Click on the drop-down to list other installed Add-ins.
On my part I choose Exchange CLient Extensions. then Click Go!
Add-in Manager dialog Box will be presented to you. Uncheck the plugin you have recently had errors. In my case it’s ESET outlook Plugin.
Hit OK. and We are done.
Thanks for reading. Let me know if you have questions. Please write it on the comment box provided below.