Computer crash after loading client

For the last day i've been logging into my account, i load the client and it's fine, click launch no problem, type in my login and proceed to login and it's fine. As soon as it tries to load the chat service my entire computer freezes, it freezes at "Logging into chat service" and after a few brief seconds of being able to use my mouse it completely freezes and i can't do anything but turn it off and on. Please help i don't know what to do or why this is happening. -Hawka