"Manage Add Ons" window keeps opening randomly

Hi,
Not really ?
There are of course key board shortcuts to open the dialog,
Possibly your Alt key is sticking ?
Alt+TA will open manage add-ons,
You can also see if the issue happens using clean boot,
https://www.sevenforums.com/tutorials/179159-troubleshoot-application-conflicts-performing-clean-startup.html
Cheers.

What were the results using clean boot ?

Hi,
The first thing I suppose we should try is reset,
Export Favorites to html file before resetting Internet explorer/ just to be safe.
https://www.sevenforums.com/tutorials/86795-internet-explorer-import-export-favorites.html

Tutorial of Resetting Internet explorer,
https://www.sevenforums.com/tutorials/1222-internet-explorer-reset.html
Accessing Internet Options from the Start menu search,
Reset process first opening Internet explorer

Okay fair enough it most likely wouldn't do any good if clean boot is not doing any different

Click Start and type in the search box,
msconfig
Click on the suggestion on top or hit the Enter key,
Go to the Startup section and take some screen shots for a complete list,
Go to the Services section and on the bottom left Check the box to Hide All Microsoft services,
Repeat the screen shots,
See the links above my signature on how to take and upload screen shots here,

Also lets see what is actually listed in the manage add-ons window,
Make sure Show All add-ons is selected on the bottom left column,

grreatpop I didn't see the kitchen sink in there. :)

Take a look at # 8 in this tutorial by Brink.

Optimize Windows 7

This is mine.