Hi, I have just installed a current ns release 2.1b4a into my computer(under Sun 4.0). It has passed the validation. But when I run some examples downloaded from Marc Greis's tutorial web pages, nothing happens but just enters the ns environment. There is even no error message or other prompt. Do you have the same experience? Can you do me a favor to tell me the solution? Thanks. Sincerely, Rui