I've had to log in twice today and even though Firefox is set to remember my username and password here I've still had to type in both for each log in.
This could be a result of security updates that were recently installed. Please check the main thread about this and see if the problem is solved after performing the in the OP suggested actions @medassin and @Ishtaron.
This thread will be locked and redirected to the main thread about this problem.
