Students can not log in

Hello, I have several students who can not log in.  They usually can hit log in and continue with google and log in just fine.  Now, several students who can not log in with continue with google and it says "you are currently logged in to another google account.  Please log out of that account and try again".  They are not that I know of logged in to another google account and I had both restart their chromebooks and still had the same issue.  Any help would be appreciated.