WordPress.com account

Hi

I have just activated Jetpack but may be missing something very obvious!! I am completely unable to create a wordpress.com account – I get the sin in / create account screen but when I try to sign up for an account I fill in the email/username/password boxes but when I click to ‘sign up and connect’ – the email and username boxes turn blank again?
Is there something really obvious I am not doing?

Thanks

Tim