How to protect from DOS attacks in Yahoo Messenger?

Hello everyone. I was wondering whats a good program or some good info to prevent people from kicking me out of Yahoo chat rooms or performing Denial of Service flood attacks which come in the form of flooding my system with endless Yahoo chat windows. I can stop the attack by closing out the program but have to reboot in order to get things working correctly. Even though I have a vague idea whos doing it and they don't seem interested in my account as a security measure I changed my Yahoo password anyway just to be on the safe side. I know it's a person in the chat room I go to who hates what I have to say and they only seem to kick me when I get on mic. Is there anyway to block these attacks I have ZA but since the attack is coming through Yahoo Messenger which is cleared to run I cannot block the attack itself I need a new way to prevent such attacks. Some people in chat mention anti hack programs but I wanted to come here first in order to be on the safe side as this is a legitimate support website. And Merry Christmas to all and a Happy New year to all! Otherwise I have no problem with my account. It only happens when I log into the chat room and a have a small list of suspects they do it to annoy me.