Sometimes regular applications are detected as threats and security applications might block them. Sometimes, these apps are actually ok and they're considered to be a false positive. Open Norton Security and check the Quarantine zone. Right-click the application blocked and add it to the exceptions list. This will allow the software to start properly the next time you want to launch it.
It's also recommended to scan the installation folder of the RMS Express application. In the case of a possible infection to clean the content.