Error when loading Outlook

I reinstalled all the apps on my laptop and I loaded Outlook and got this error message:

“The add-in could not be installed or loaded” error message when you start Outlook

What to do? Do a search for Extend.dat, it should be in the same folder that your *.PST files are in. Once you have found it, rename the file (or delete it) and restart Outlook. The Extend.dat file is a binary file that caches registry entries for third-party product extensions.

So what was installed that made this happen? I had some bluetooth software installed that tied my cellphone data to my outlook data and since that wasnt installed it started to give me errors. This could also happen with anti spyware and anti spam plugins for outlook that you no longer have installed.