GUI login continually advises 'session expired'

Hi folks,

From this morning my time my Safari login to my XG proceeds as far as the GUI, then sits spinning the wheel while showing 'session expired'.

I can login using FF without an issue.

I have restarted my MAC a couple of times to try an see if that kills the session, but no, I have changed the timeout on the GUI so it automatically closes an open session after 10 minutes, that hasn't worked.

Beside performing a restart of the XG, does anyone have a suggestion to clear the stuck session in the XG GUI?