Identity Safe log-in combination fails through Firefox

Identity Safe is failing to fill-in and sign-in for my AT&T Yahoo email account.  This problem also happened a few weeks ago.  This is either a problem in Firefox, a problem in N.I.S., or both.  We should not need to remove a specific log-in combination and reset it manually, if that would be the remedy here. 

 

FireFox 10.0.2, Norton Internet Security 18.7.0.13

Windows XP sp3

(Note this is with In Private browsing mode of Firefox)