This isn't strictly Ubuntu-related, but it's a perplexing problem and maybe someone here knows now to solve it. When I have the NoScript add-on enabled on firefox, then my university email won't work - it lets me get as far as the screen saying I've successfully logged in, but when I click the 'continue' button, firefox freezes and goes grey. I have all university sites marked as safe, so NoScript shouldn't be interfering with them, but only turning it off completely seems to sort things out.