Sorry for the trouble!
We're seeing some Pinners having trouble logging in on Internet Explorer. If you're using Internet Explorer, make sure your browser is up to date. You can download the latest version here: http://www.microsoft.com/en-us/download/internet-explorer-10-details.aspx
Or, you can try from a different browser! You can find Google Chrome here: https://www.google.com/intl/en/chrome/