I had a problem with a site when upgrading to WP 3.3 PHP 5.3 that I wanted to report here becuase I could not find any information about it.
The WP posts and WP pages edit pages were showing corrupted multiple version of the same post and special characters in the post titles.
Also all the front end hyperlinks from menus were broken, pointing to 404 page not found.
The problem was a conflict with the plugin advanced category excluder and after deactivation the problem was resolved.
Hope this helps.