All my blogs are on the same server. The Dashboard always worked with 1.5. It was only after upgrading that the dashboards started exhbiting the strange behaviors.
I could have sworn I saw a reply to a post here where someone said they made a change to the CSS of the page that displays the dashboard, and that made the dashboard show up. Alas, I can not find that post!
I honestly don't think it's a transmission problem - with my blogs at least - I think it's a display problem. I could see it being a transmission problem if some of the lines dropped out or something, but sometimes the text is "invisible" until I highlight it [which indicates to me that it's received, but not displaying correctly], and sometimes the display will just have a "square" of text - literally, a square shaped chunk of text. To me, those connote display problems. But I have no idea how to fix it, and no confirmation that I'm anywhere near correct... so I gave up.