Posts won't save in composer

We installed EasyBlog on a development site for a domain that we were upgrading from J 2.5 to 3.x. No problems - it worked perfectly and we were able to create/edit posts. However after changing the URL from our development domain to the live domain, we can no longer save posts in the composer. The popup appears and says "Saving your post, please wait." The progress bar moves about 70% across, then stops.

I've tried changing editors, browsers, uninstalled/reinstalled EasyBlog - no change. None of the files or permissions have moved between the development site and live version, all we did was update the domain name in cPanel.

Any ideas?