This same thing is happening to me as well. I use fire fox, and I'm able to sign in but once signed in I can't navigate to other folders and the most annoying this is I cannot open my emails. It doesn't say anything about an error, it just high lights as if it's not a link to my email. I've tired everything! And now after reading saraneth's comment I'm downloading Internet Explorer. Haven't used it in years as well! I just don't understand what's happening, could my computer be at risk and it's trying to protect itself?