Pro Sites settings page not found error

Hi;
The pro sites plugin settings page gives a page not found error when the save settings button is clicked. This happens on the default theme which I switched to just in case the site theme conflicts with it. Other pages of the plugin work fine. Has anyone reported this problem? I disabled all the plugins and still no luck. Using WP 4.0 here. All features of multisite are running just fine by the way.
Thanks..
KP