When I first posted a thread like this one months ago, it caused bad arguments. First, I am sorry for being so childish in my first thread about ports. Then I want to ask those questions again with a few different ones:

1. I suspect(no, I know) my MSN Messenger has been hacked. I can still login to gmail and passport.net but I can not log in to MSN Messenger. I'd like to know if somebody can use TFTP and MSN Messenger(he didn't even talked to me in MSN) to hack my MSN Messenger?
2.If so, are there certain ports TFTP use? Can they be detected and listened(code of freeware please...)? Can I refuse incoming data from the listened ports(code or freeware please...)?
3.My father told me MSN Messenger would have caused some security problems.
4.I don't want to use ZoneAlarm(it would interrupt me too much).
5.Can somebody teach me how this port stuff works?