I've got a weird problem. Suddenly my Magento shops gave an error 500 when I try to open a catalog page or a product page. CMS pages are working stil fine and if I disable compilation in the backend, everything is working fine again.
What could this be? How to trace down this strange error? I already tried to set the show errors option in index.php, but instead of giving details of the error page it shows a blank page.
Already tried to flush cache reload indexes and checked if something changed at the hosting platform. Flushing caches and reindexing didn't work and nothing changed at my hoster.