win 7 Pro. x64. FF up to date. have reviewed most of the pertinent tips and etc. There seems to be a key underlying question: should sync open using the accounts.firefox.com? There is one web address for support. A different one for accounts. Should I set up another for sync? The instructions do NOT make that clear. The error msg at sign-in using accounts. password is: 'unexpected error'. Well sure!!!! But quite useless info! Problems with sync are long standing and I quit from exhuastion and other surpassing demands. we try again. I strongly suspect that the problem is simply the correct password for the correct account---which would indicate: set up a new account: sync.firefox.com or such and with a new password. Is this correct? Once this is resolved, I can move on to other open tickets/questions of long standing!