524211 Joomla fixes

I have a joomla site with some problems... 1. Our chat feature is only working in older firefox programs... The chat bar shows in FF 6.0 BUT it says you are not logged in... in IE and chrome the chat bar is total missing... 2. Clicking on many of the links or features in joomla causes the user to be logged out with the error that their username and password do not match.... I need immediate assistance fixing these issues from a joomla EXPERT!