Java – GWT Hosted mode : Connecting to 127.0.0.1

I've recently started to see a hang when testing GWT apps running in hosted mode. It hangs with the message "Connecting to 127.0.0.1"

The only solution is to stop and restart a few times. Has anyone else seen this?

If so, any ideas about the cause? I wondered if it was a firewall block. I'm using Zonealarm. If you are also seeing this, please add a comment to this question mentioning which firewall you use – maybe a pattern will emerge.