Installed 2.6.1 and now can’t expand “Advanced Options” for on “write new page”

Hi,

I have upgraded to 2.6.1 and now can’t expand any of the “Advanced Options” when writing a new page. e.g. custom fields, page template etc.

I have tested with IE, FF and Sefari. Has anyone else found this?
Sefari status just keep loading and changing from “loaded 63 of 64” to “loaded 64 of 65” etc and the options never appeared.