Book links seem random

Sometimes when I follow a link to a book page from a Drupal module page, a seemingly random set of book navigation links are expanded on the left. I would have thought the selected node should be expanded and highlighted and all others collapsed.

For example, the following two links:

http://drupal.org/handbook/modules/pathauto
http://drupal.org/node/101723 (CCK)

Both have the following links expanded:

# Comparison of Similiar / Relevant by term block modules.
* Installation and setup
* Lightbox2 - Howto add a lightbox to your images and other content
* Adding functionality to your forum with contribs
* Styling your forum
o Lightbox2 - How to use with Gallery2
# Contributed modules
* Lightbox2 - Installation
* Lightbox2 - Keyboard Shortcuts
* Lightbox2 - Known Issues
* Lightbox2 - Settings
* Lightbox2 - Translation of configuration strings
* Lightbox2 - User Permissions

Surely this is not right?