I had the same problem with the emails notifications being sent out correctly but the spinner running infinitely, and I am using WP3 and the default theme at http://www.cyclesummit.de/konferenz/anmeldung/
After I deaktivated all other plugins cf7 worked fine again and showd the green message.
Thanks Takayuki Miyoshi, excellent plugin!
I am using it and it works well – except that I am no longer able to use a RSS-Reader to watch its articles and comments.
Is there an alternative way of reducing the number of readers /writers to those few I want to have as user BUT at the same time allow them to follow the blog with an RSS-Reader?
Thanks for any help!