In Firefox 1.5, "<code></code>" blocks inside lists (ordered and unordered) sometimes appear with the bottom border missing. By sometimes I mean "some always display OK, and others always display without the bottom border", not "sometimes the bottom border appears, and other times it doesn't".
To see the bug in action check item 5. on this list:
http://wiki.splitbrain.org/wiki%3AInstall#mac_os_x_and_apache
I'm unsure if this is a bug in the HTML code generated by dokuwiki or a bug in Firefox (it worked ok in Firefox 1.0.7), so I also reported this to them:
https://bugzilla.mozilla.org/show_bug.cgi?id=318581