It seems a lot of user upgrading to WordPress 3.0 are having this issue. It is simple to fix, just go to the edit screen and use the screen options (tab at the top), and set the Screen Layout Number of Columns: to 2.
Novice Users: People who are afraid that simply pressing a key might break their computer.
Intermediate Users: People who don't know how to fix their computer after they've just pressed a key that broke it.
Expert Users: People who break other people's computers.
- 504,629 thank you akismet