Dashboard screen options not saving or displaying correctly

I am having trouble with the screen options in a newly upgraded install of WP 2.8.4. Though I have it set to show 2 columns, everything is still displayed in one column. There is space for the 2 columns, but the right column is blank rather than showing the Publish and Attribute boxes.

My client is having even more trouble in that when she sets the screen options to show 1 column, it won’t hold. When she comes back it’s on 2 columns again.

I’ve disabled the plugins and tried the default theme, but nothing is working.