I've been having the same issue since I upgraded to 3.3.1. Tried everything--reuploaded manually, reinstalled, cleared my cache, etc. I don't think it fixed the issue. After a day or two, I found that my dashboards are fixed again, yes, dashboardS, because all of my wordpress blogs are having the same issue. However, sporadically, LIKE NOW, the broken dashboard is back again and I got totally lost already what's wrong.
What I do, though, is WAIT. lol. When the dashboard is broken, I WAIT a couple of hours or a day because it gets fixed again. There's nothing else I could do. But that sucks, because of course you can't always JUST WAIT. WordPress people have to fix this! They already know that all the suggestions they give us (re-install, manually reinstall, upgrade, etc etc) do not work. Something's really wrong with 3.3.1.