I had similar hanging problems. The plug-in seemed to work for a while, but then the Preview button stopped working while I was working on a new post. I decided to Publish it anyway, and then the whole blog froze (though other blogs on our WordPress MU 2.7 installation were OK). I attempted to deactivate the plug-in. That eventually timed out with a failure error… But then for whatever reason it and the symptoms disappeared, so maybe it did manage to deactivate. I have deleted Tweet This from our system.