[wp-hackers] Categories empty on all blogs after PHP upgrade

[Hacker Scot]

OK, here's a weird one. Upgraded PHP 5.2.8 to 5.2.9 on a server today.  
The server hosts 90 WP sites on 50 or so domains. Immediately  
afterwards, all categories on all blogs are empty.

wp-admin/categories.php lists all categories with the number of posts  
in each; click on a category and it shows zero posts. Same on the  
public/front-end. If I then run Repair Tables via phpmyadmin,  wp- 
admin/categories.php shows zero posts in each category, same on front  
end. In other words, repair tables seems to make things worse.

All WP installations are 2.7.1. None of them were upgraded. This was  
just a PHP upgrade on a cPanel system with MySQL 4.1.22.

Findings lots of solutions in the forums for fixing individual blogs,  
but nothing about server-wide category problems.

All suggestions very welcome.

Thanks,
./s