For some reason my main level pages have become (for the most part) 403 forbidden. Their child pages still work.
The blog: http://www.adyar.nl/
A page that is not working correctly: http://www.adyar.nl/tvn-info/
I'm using redirection and role scoper. I tried disabling role scoper, but that doesn't change anything.
I tried editing my .htaccess file (with redirection disabled) but that only made things worse.
Other plugins installed:
Breadcrumb Titles For Pages
Flexi Pages Widget
jQuery Lightbox For Native Galleries
Sitemap Generator Dagon Design (adapted by me)
WP E-Commerce Dashboard
WP E-Commerce Shipping (Country, cart amounts)
WP Shopping Cart (aka wp e-commerce)
WP Super Cache
I have no idea what to try next.