I upgraded to WordPress 2.0 shortly after it came out. On one of the sites, on the Write Post screen, the ability to reorganise the boxes about isn't available, the trackback fields and Post Preview aren't visible and the AJAX features like adding categories on the fly don't work. In fact, the textbox for adding categories is also missing.
I've tried re-uploading the files, disabling plugins and running the upgrade script again, but nothing has resolved this problem. It also exists when logged in as different users, on different machines and in any given browser.
Like I say, I've had two other successful upgrades. Just this one playing up. Any ideas, or anyone else experienced this?