Did you check table IX-A3? I want to know what other plugins you have active and that should be possible when you check Table IX-A3. Do you have any chaching plugin active?
I checked that box (it is still checked) and tried again, but the error page still shows up. I do not have any caching plugin active right now. Any other ideas?
These are your active plugins:
all-in-one-seo-pack/all_in_one_seo_pack.php *
anything-popup/anything-popup.php *
breadcrumbs/yoast-breadcrumbs.php
category-posts/cat-posts.php
google-sitemap-generator/sitemap.php
hotfix/hotfix.php
nextgen-gallery/nggallery.php
nggSearch/nggSearch.php
pagemash/pagemash.php *
search-and-replace/search-and-replace.php
spam-free-wordpress/tl-spam-free-wordpress.php *
wp-db-backup/wp-db-backup.php
wp-downloadmanager/wp-downloadmanager.php
wp-dtree-30/wp-dtree.php
wp-members/wp-members.php
wp-page-widget/wp-page-widgets.php
wp-photo-album-plus/wppa.php
wp-table-reloaded/wp-table-reloaded.php *
youtube-embed/youtube-embed.php
I pplaced a * behind those of wich it is worth trying to de-activate to find the problem
