I'm using CF7 2.4.2 in WP 3.0.1.
I've been having the more than common problem of the spinning arrow when submitting the form.
After trying out some of the fixes presents on different threads of the forum without success, I just realized that in my case the problem only appears when I access the page containing the form using the domain name that redirects and hides the real address.
You can see what I mean here:
Original url with the form working fine:
Domain redirecting url, with the spinning arrow problem:
I'm running out of ideas..