Hey Peter,

  I'm working on getting this old version into my lab (unfortunately all my machines are running the latest code, and in some cases the 6.2 ctp code and modules).  So, if I can get the time to get another portal up and this old version I will see if I can actually duplicate this, but in the mean time without recalling the actual interface, the first thing that comes to mind is checking forum settings, and verifying that you have it setup for 'Public No Moderation'  or an otherwise public setting.

 Also, I ran into an issue on another module installation where by default it sets all of the newly added modules to inherit the parent page perms, and the page I was on was hidden to the public view, so no matter what I did unless I was registered and logged in I couldn't see it. Once I removed the ' Inherit View permissions from Page' option in the module permissions settings I was able to view it as an unregistered public user.  Of course set it to match your requirements for registration etc.

 Hope That Helps!

Make It A Great Day!

D-Man