Page not found error on creating Vocabulary

I'm following along in the bowling screencast. After I create a vocabulary, I'm redirected to this URL:

content/bowling/html

which gives a "not found" error. However, the bowling node is listed in admin/content. Clicking on its link in the title column produces the same error. However, clicking on the edit link in the operations column opens it, and after resaving, clicking on content/bowing redirects to content/bowing/html and the page opens, which is the expected behavior.

Creating a class from the vocab page works as expected.

I'm using Drupal 6.11 and MySQL on CentOS.