Why has "login keyring" suddenly been activated?

Maybe you activated the automatic login option ? (without password or login screen).

You can clear up the passwords (leave them blank) with seahorse program.

Open a terminal and write:

seahorse

See this picture

http://i.stack.imgur.com/VK0Ii.png

Click on change password and use the current password (your password) and the next fields , leave them blank.

Thanks

I ran seahorse and did not get the same screen that you did. I got this:

file:///home/john/Pictures/Selection_001.png

I clicked the green + and got this:

file:///home/john/Pictures/Selection_002.png

I selected Password Keyring and got this:

file:///home/john/Pictures/Selection_003.png

I typed in a password and restarted the PC. When I open Firefox again the same login keyring box opened.
I seem to be going around in circles.

Sorry, My screen shots don't seem to open.

You must upload the pictures to a free hosting site such as

http://imgur.com/
OR
http://imageshack.com/

and then give here the links.

Try to disable autologin option and see if problem fixed.

If yes , then is what I said.. you must clear up the passwords from "seahorse" program.

See here another example

http://askubuntu.com/questions/867/how-can-i-stop-being-prompted-to-unlock-the-default-keyring-on-boot

Thanks

I ran seahorse and did not get the same screen that you did. I got this:

https://lh3.googleusercontent.com/-EN7TOCFzc3o/UQ6E0yYJE9I/AAAAAAAAE0Q/ZbHcAWVTS-A/w320-h250-n-k/screen%2Bshot%2B1.jpg

I clicked the green + and got this:

https://lh3.googleusercontent.com/-1JJ5ClHQA2E/UQ6Ex5MtlOI/AAAAAAAAE0A/TYTQLUXVATs/s535-p-k/screen%2Bshot%2B2.jpg

I selected Password Keyring and got this:

https://lh5.googleusercontent.com/-z2sFBap_lqk/UQ6EzHWmMaI/AAAAAAAAE0I/z3VfsVX4Oak/w320-h250-n-k/screen%2Bshot%2B3.jpg

I typed in a password and restarted the PC. When I open Firefox again the same login keyring box opened.
I seem to be going around in circles.

Lets see how Picasa pix work.

Disabling Automatic Sign In seems to have solved the problem.

Thanks for the help
John

Thanks NikTh, that solved my question.