My current primary business is IT consulting, which really means that I spend most of my time working face-to-face with people that have trouble with computers and technology in general. So, this kind of behavior isn't news to me. In fact, I've tried often to convince the tech-savvy that most users have problems like this, and I've never been all that successful. The RWW "Facebook login" is great from this standpoint…
The funny thing is, you can turn most people away from the computer and read the error message verbatim (or any other dialog) and they'll be able to answer you. It's merely the fact that it's displayed on the computer that confuses/scares them. Once they've answered you (say "Yes, I want to cancel") you can turn them back to the computer and they'll still have trouble picking the right button.
There is some kind of mental block here -- but I believe that most people can get past it if they're forced to interact with computers. I rarely just click on a dialog for people -- I make them read it. I make them think about it. I make them pick the right button -- over and over. Eventually they gain more confidence and can do it themselves. And slowly they do begin to "get" computers. Dropping someone into facebook without them having the confidence is probably never going to work. But smart people don't have to be dumb with computers.