the latest java update seems to have broke the beta client... the regular client works fine.
Could you try deleting java temporary files and trying again? You find that under java control panel, which you can access from windows control panel if you are on windows. You can also reach it by running "javaws -viewer" from command line on any OS. I had this problem when switching from java 6 to java 7 on a Windows machine.
the site is still unstable as hell...
A couple times today there has been 1500+ more connections than usual and 3-4 times the normal CPU usage. Not sure yet what's causing it as I haven't had the luck to watch it as it happens.