Collapsibleblock seam to break all JavaScript

Is there a bug in Collapsibleblock 5.x-0.4? When I activate it, I notice that all JS is broken on my site.

Firefox 2 displays this error:

Error: $.cookie is not a function
Source: http://url-to-mysite.com/sites/all/modules/jstools/collapsiblock/collaps...
Line: 31

My system:

Drupal: 5.1
PHP: 5.2.0
MySQL: 4.1.22

Please let me know if there's anything else you need to know.