Instant Messengers

Alright. I got DSL couple months ago. Before that I had dial-up and everything was working fine except for the speed. I was easily able to log on to all the instant messengers that I use (MSN and AIM). Since I installed DSL I can’t log onto either messengers or any other messengers such as Yahoo, ICQ etc. etc. I have cleard temp. files, DNS cache, etc. etc. but no use. What should I do? Should I reinstall windows xp pro? I am using xp pro right now.