>It does'nt happen each time, only intermittently. When it does, it is exactly as you describe above...

So, when you say you have it on random basis, it is always when you click on Log in right? I assume this is the case. If that is the case, could there have been a chance that a click was done on "Try it before creating an account"? Do you also remember if there was another login with another browser between those situations?