When you are on your Chrome book please open the chrome web browser. At that point please go to the chrome control panel.  (The three little lines on the top right of Chrome.) Once you click there please go to Settings. At the bottom of settings click Show advanced settings. Then go to Privacy and select Clear Browsing Data.  A dialog box will pop up.  Please choose the third and fourth options,  Cookies and other site data and Cached images and files.  The rest of the check boxes are optional. Near the top please select Obliterate the following items from: The beginning of time.  At the bottom select Clear browsing data. At that point please close out of the dialog box if it is still open, close out of settings and chrome. Re-open chrome and try to log in again.