Adding a PayPal/RSEvents/RSMail/reCaptcha field hangs up

Each time a want to add a PayPal/RSEvents/RSMail/reCaptcha field a red loading text appears, it hangs up and never saves.

This can happen after a update of RSform!Pro or one of the specified components (RSEvents and RSMail) and you're using out-of-date versions. One can resolve this by simply, uninstalling the plugin in question (PayPal, RSEvents-RSform!Pro, RSMail-RSform!Pro, reCaptcha), download it directly from our site (my paid downloads area) and install it again.