tcpListener.Start() Freeze Problem

Ok guys, this problem is giveing me a headache...spent hours on it.
When the code tcpListener.Start() executes, the UI goes unresponsive. And to fix this all i need to do is execute this in a new thread.

But i tried this, and that didnt fix the problem either. Then i read about background worker...i tried that and that didnt work either. You'll know what i maen when you look at the code:

http://download.yousendit.com/D10489FD3E4F16B6

This is a school assignment :p due monday
fingers crossed i find a solution to this by then.

So whats the problem with the code?