I keep getting the login window pop up even though I have successfully logged in

I have the same problem on my 520.   It looks like It doesn't like my password, however if I logon once and ignore the additional logon prompts, in the window behind, it says I need to do an update.  If I do the update, it does sync, one time.   Each time, it seems to want to apply the same update and the logon issues comes back over and over.