I am having the same problem and have documented it in a post two hours later than an yours. I did not find your post when I tried to investigate the issue. I was first concerned that a spying app had made it into my system and was posting the Password entry window but later proved that it was a Firefox function being activated. My opinion is that this is a significant bug. The Password request has popped up twice while I was entering this note. For tech support, you have another bug. I clicked the "I have this problem, too" block and the "Thanks" Message is covering a portion of this Reply box. I have had to temporarily add a row of input in order to see my Reply message (I will now go remove it). There must be a better way to report bugs. (?)