Coming in a little late...

~~dusty~~ ... have you been able to access chat before this? On whatever computer you've used before? Has anything changed on your computer - anything at all - have you downloaded something new, removed a program, anything like that??

I think I've come across the "Authentication Failed" before... I think it's something about the server timing out - so you can't get in. It may have nothing to do with your account or computer. My suggestion is to reboot your computer, and try again to access chat. Sometimes that works for me.