WSOD for Editors

Hi there,
I’m working on a large site with a large amount of pages, and some custom post types. Everything works fine as an Administrator, but as an Editor it’s not possible to view pages (edit.php?post_type=page). I just got a white screen of death. Strangely enough, when I view a custom post tyope (edit.php?post_type=custom), it just works.

– I cleared the whole database and it works.
– I repaired the database in phpmyadmin (although I’m not sure if that was needed.
– I tried deleting parts of the database, but I couldn’t pinpoint a single entry that may have started the error. Even if there are just a few entries it will give the WSOD.

Other WP Installs on the same server experience similar (but a bit different) errors when logging in with another User. So my guess is that it has something to do with the server configuration. I know the keep-alive was recently changed; but how would that explain the fact that it’s only a problem with editors and only with ‘pages’?

Any help is much appreciated.