Preparing to install what?

I don't use it for much, my preferred browser being Firefox, but on the occasions when I launch Internet Explorer, or open a new tab, a box pops up and disappears almost immediately. It took a lot of times before I could see the words, "Preparing to install" and I have no idea what it is. Nothing gets installed, as far as I can tell, and no unexpected tasks are ever running.

It's a mystery to solve, I guess.

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