download problems on linux
 

hello.i am using fedora core 3.I opened a tcp port (written in program's prefence) and i opened my host using DMZ option of my router adsl modem.When i run program i can connect to server and i can search.but when i want to download something,status is waiting and waiting.Then if i do something (clicking something or want to stop program) all the things on window dissepares and i can not stop the program.i mean it locks.it can be about my routers option or opening wrong port i dont know..what is happeneing? and what must i do?