Strange white space on dashboard, white text in posts?

Just updated my blog to the latest wordpress beta. Did the same thing to my developer blog a couple a day ago and everything went fine with that one. But not with this install.
I’ve used the beta plugin, reinstalled the beta a couple of times but there is no change.

If I login to my dashboard I see a big white space at the top: https://yfrog.com/h3jd6tp
When I wan’t to edit a blogpost all my text is white, there is no wysiwyg editor and there is still a big white space at the top: https://yfrog.com/18w1tap
I do see the upload/media button but when I click it I get a messed up upload screen: https://yfrog.com/h0hwwdp
Looks like the installation didn’t complete? Is there a way to do a safe reinstall of wordpress? Or do you people know this problem and do you know a solution?

Jonas Smets