Wait long time for OK button after Finished Processing Updates

Why does such a long delay happen between "Finished Processing Updates" and the appearance of the OK button?  This question is about both Norton 360 AND Norton Internet Security.  I find this delay occurring in more than one product on more than one computer:  Norton 360 v 4.3 on Vista; Norton 360 v 2.5 on Vista (but different machine); NIS v 18.? on XP s.p.3.

 

I'm interested to know what happens between the first message "Finished Processing Updates" and the appearance of the OK button.