I recently had a talk with person that was doing sort of QA for my app. There was one topic we strongly disagreed on. He basically said "don't throw user a pop-up in his/her face if he/she has no option of doing anything, example 'OK' modals".
As an example (please disregard if it's neat to use system-looking message box):
How I explain those modals is that there are certain information that I want to make sure user noticed.
He said that it could be written somewhere without "throwing it into user's face". Well, I didn't make the experiment but I think on the screen below, I could write "We must also check which, by the way you are full of shit components are already installed". And I can bet $50 that he (and most average users) wouldn't even notice that. That's because what I see is that users don't read even short messages (not to mention the long ones). They just look for next button to press.
I just don't want to finish action that was taking some time to complete and remove this "progress" screen without any notification whatsoever. Also I think that Windows already prepared average users to the "OK" pop-ups so that they won't be confused like "what am I OKeying?"