I had no problem with upgrading from 2.7.1 to 2.8.4 on sites where I had Atahualpa 3.4.2 already installed. On my main newspaper site, where I have a very customized version of Atahualpa 3.2 installed, I upgraded to WP 2.8.4, and found out the site had been hacked back in July, and it showed up after the upgrade.
Anyway, after a very expensive fix, the site is working, but the dashboard is not. Not well, anyway.
We can't add tags to posts. We can't use screen options to remove features, and we can't move the panes around.
I've tried activating the default theme, and it didn't help. On advice from the WP support forum, I renamed the plugins folder. No change.
I don't know what else to try. Anybody else have this problem?