And it doesn't happen... Instead I am getting some pop up contact manager... or something similar. ( open contacts popup )
What theme are you using Chuck? The default (red) one? It looks to be in order on my end.
And now it works, again????
I haven't changed anything on my end. I've noticed some funkiness on drop down menus across all vBulletin forums. If you accidentally click and drag certain way it it falls back thinking javascript (which is how the menus work) is disabled. I've never been able to figure out exactly why it happens and it doesn't do so gracefully which is a failure IMHO.
I don't want to tell you how to surf but using the "New Posts" or "Unread Posts" link is better for people who visit frequently. It keeps track of what threads you've read, haven't read, and where in the thread you left off so you don't waste time accidentally rereading posts you've already read (not that I've ever done that.)
Have you tried clearing Firefox's cache? Tools > Clear Recent History > Everything. That should get you back to normal with Firefox
If not backup your bookmarks and delete your firefox profile folder (http://support.mozilla.com/en-US/kb/Profiles#Where_is_my_profile_stored_). It will create a new one when you restart and should clear up any issues.
Barring either of those two things working download a fresh copy of FF and reinstall.