As I started on Drupal I came across an IBM tutorial that explained how to setup a Drupal developement environment with Eclipse. What they did was setup a virtual host in Apache by the name of 'drupal.development'. That worked fine in Firefox and I was happily configuring Drupal when I decided to use Safari to test the 'anonymous user'. Whatever I tried, I got an 'access denied on /' error, not even the Drupal page I specially set up for it, no, just a plain white page with a single line.
At first I ignored it, but as I progressed in the configuration I wanted to test more and ran into this issue. Reading up on possible causes I verified that the vhost conf file was in the right directory, I also verified that it had the correct permissions and what's more: Firefox just worked!
I'm not an Apache guru, but it turns out the allow/deny settings in the default httpd.conf had to be overridden in the vhost file with 'allow from all' (and strip anything referring to 'deny').
Beats me why Firefox happily served pages where Safari was just stubbornly denying everything.