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.
Any ideas?