Why can't I sign into Fluther with my usual computer?

I use an old Dell D610 running XP to go to this site. It has been working properly for at least 6 years. Last night I signed in using a new Kindle Fire and it worked great. I said I was in desktop mode and could read everything an respond.
However, when I tried signing in with my laptop I could not! I entered my name and password separately but that did not work. I cleared cache, I tried restarting. That did not work. I tried a different laptop, Dell E6440 running Win 7 and that worked. I made sure to log out with the kindle. It made no difference.

When I use to the old, usual laptop and go to this site the name and password pop up. I select those and click Login but nothing happens.
What is going on? What changed? Is there a setting I do not know about?
Any other suggestions?