We need more details. What happens? Does the game crash? Does it just close unexpectedly with no crash report? Do you get any pop-ups saying "This application has been blocked?"
If the game is crashing, please post the report you get. Without that, there's not much we can do. Otherwise, try to give us some information about your system such as operating system (include version), any firewalls or other security/antivirus software you have, Java version, hardware information such as graphics processor. You might want to search your computer for the crash file if it isn't popping up. See this thread for instructions:
viewtopic.php?f=47&t=44631&p=579684&hilit=dump#p579646
Opinions expressed in this statement are the authors alone and in no way reflect on the game development values of the actual developers.