Any ideas as to why I'm getting this after installing. This is a fresh install and I've logged in for the first time. Should I do a clean install?
Is there a proxy server between you and the Matrix server? It looks like you're losing your login session (perhaps due to an IP address change, which can happen when you have proxy farms).
You can set "Allow IP Address Change" from the System Configuration screen or directly in main.inc to see if that solves the problem.
That did the trick, thanks Avi.