In this topic Matt states this bug has been fixed. This was a Beta 2 release and he said it would be in Beta 3, however, Beta 3 for me still doesn't allow the admin panel to load. It sticks at the redirection screen in IE and FireFox.

This is very frustrating, as I cannot test out the new features properly.

It only freezes when loading the tab.

It still does it for me as well.

Hack it. You do high end websites, you should be able to hack through the problem in only a few minutes and get on with looking at the beta preview. It's not like this is a production version or anything.