Right, I understand how the color change happens on mousedown.

My point is that I'm reasonably certain that I'm not moving the mouse between mousedown and mouseup. In other words, I made a perfectly valid click. And I can tell for sure that IE got at least the mousedown event because the color changed. So why is it eating the mouseup events and not following the link?

Let me strengthen the above statement. I am absolutely certain that the mouse is not moving between the Down and Up events. I have watched several failed clicks carefully, making certain the mouse pointer did not budge.

Also, if it were a general problem with my dexterity, I would be missing clicks in other applications. I am not. The problem only happens in IE as far as I can tell.