>>>>> "W" == William Djaja Tjokroaminata <billtj / z.glue.umd.edu> writes: W> Although currently the problem has been solved, I don't know whether there W> are other "time bombs" still lurking in my code. That's why I am asking W> the rule of when it is necessary to protect the global variables. Is it W> that such a rule does not exist that you need to see the actual source? No, these rules exist but I don't want to formalize them because I don't speak english. When you ask for help, it's best to give the maximum of informations, otherwise you'll have only useless responses. Guy Decoux