I have the same issue, however it look like it is a problem with one of the servers used for the login. https://status.salesforce.com/status/NA3 You can check the URL to see what server that are doing the authentication: https://na3.salesforce.com/services/auth/sso/....
You can check the URL to see what server that are doing the authentication: https://na3.salesforce.com/services/auth/sso/....