The problem has nothing to do with your computer or your settings. It has to do with messenger not being compatable with XP. I have had XP for about 2 months. At first I could get it to work only with an older version of yahoo. Then that quit and it's not working at all, and hasn't been for weeks. When I go thru the wizard everything works fine. I can voice chat in an IM, just not in a chatroom. Go figure. I went to a yahoo help page and it listed out the operating systems that Messenger is compatable with and XP was not on the list. Yahoo needs to wake up and discover they are losing a lot of customers. If you're interested in trying out an older version of Messenger, go to
http://www.freecreed.com and in the search engine type in "messenger archive" and that should get you to the list of other versions.