It's in this thread: "Isn't the "Send preview to this mailing" Dialog Supposed Send Preview?"
Somehow you went in and tinkered with it on our NS account.
I see where you had script errors detected in Firefox, but at the time the NS account was not updating to PM 1.02. We don't have the problem with Bluehost the installation was a sharp knife through warm butter.
I'll see if I can find error messages.