I've updated my drupal site from drupal 6.19 to drupal 6.22. After the update most of my blocks were disabled, only the navigation appeared together with 'some' primary links. Additional menus were set to the disable section. On top of that none of my views was visible in block form anymore and when I tried to go directly to that view's view page I got a WSOD. I had to enable my blocks again with all their configurations (a pain!) and I increased the memory limit in php.ini from 96MB to 132MB. Now it seems to be working again. I'm thinking to revert back to my back up and wait for a more stable release of the 6 version.
If any of you out there experienced similar behaviour I'd love to hear it.