I’‘m not sure what might be going on with the crash – Gato will have to help with that. However, this message means that you tried to use the content filter with Jive Forums 2.1.x. The plugin download page needs to be updated to correctly list the required Jive Messenger version for each plugin. In the case of the content filter, you need to be using 2.2 beta. I’'ll try to get the plugin page updated ASAP to eliminate this confusion.
Could you be more specific when you say that the server crashes? Is the process of the server dying? Is the server up but unresponsive? Could you check the log files and post any error that you are seeing?