Just had a freeze too while doing an edit; it's reproducable, but note this only happens if I try to edit the same post for a second (or more) time! The first edit will work allright
If I'm on my second or more edit and I click edit post, and then press save it freezes.
However when on my second edit I click edit post, then at the bottom of the edit screen click edit post again it brings me to an edit screen that won't freeze when I click save.
Running windows XP with IE8 and no addons.
Again, please note that when I edit for a first time all is allright, and I don't have another edit post option at the bottom of the page. When I edit an additional time, I will have a edit post option at the bottom bringing me to a new screen, and using the first screen and saving will freeze me up.