Unable to access new instance

I'm new to EC2 and have created an Ubuntu instance and assigned an elastic ip.

However, I can't ssh to it (just sits there), ping the same. Trying to acces from the control panel eventually gives 'xxxx took too long to respond.'

The instance is reported as running and healthy. I haven't changed the default 'open to all' firewall rules.

I have rebooted the instance.

What have I missed ? :)