Descriptive Problem Summary:
Just noticed this about a week ago. My "Default Display Action: Unread Messages" setting is no longer working as expected. When viewing new threads with one or more replies, I only see the first post in the thread. If I click a later post in an new, unread thread, I only see that particular post.

Numbered Steps to Reproduce Problem:
Choose an unread thread in the Developer forums

Expected Results:
To view all unread posts, regardless which unread post in a thread i have selected.

Actual Results:
Clicking on any post in an unread forum thread only reveals *that* post.

Does the problem occur:
Every time? Or how often?
Everytime under Firefox 3.5.3

When does the problem NOT occur?
When using Safari Version 4.0.3 Build 5531.9 and Opera Version 10.00 Build 6652, the forum behaves normally - ie, when clicking on *any* post in a new thread, all posts appear, as per my forum "Default display action: unread messages" setting.

Workarounds:
Not use Firefox on MacOS X 10.5 :)