This message is informational in nature, and is not indicative of an issue with SSL or the software no longer being secure. It means that you are moving from a secure zone (an https page where a supporter would expect to be able to enter credit card or other sensitive information securely) a non-secure page, such as a main page, where users should be able to access without having to enter login credentials.
This is similar to the Internet Explorer, option "Warn if changing between secure and not secure mode" located in Tools > Internet Options> Advanced
- What browsers are supported by NetCommunity for current information on browser compatibility.
- What is the recommended internet browser for Blackbaud Sphere? for current information on browser compatibility.