If you're having issues logging into your Cornerstone account, there may be a couple of reasons.
Firstly (and it might sound silly), be sure to enter the correct email and password. If you've signed up using a Gmail address you might want to check with both the "@gmail.com" and "@googlemail.com" endings.
If this still doesn't do the trick, we would recommend trying again using the Google Chrome browser in an incognito window.
If you're still having issues, then please drop our care team a line and they'll look into it for you. It occasionally happens that members signed up with an email address containing a typo and should that be the case, our Customer Champions will be able to update your login details to the correct ones, once they've confirmed some details with you.