In Upgrading to the latest Beta release of ActiveForums (currently 6.2.8) I found that the "Theme" I had running on SCCAForums was old and outdated, and using HTML Tables for layout (gasp!). 

In order to get the new Bootstrap theme going I had to remove the theme I was using, and change a few settings.

  1. Go to the Module Settings for the module, and choose the "default" theme in the settings.
  2. In the Host/SQL page you can run the following SQL to remove other settings. I also ended up finding that I had a problem with various templates that ActiveForum uses being duplicated multiple times in the database. I put together a script to remove those extra entries as well.

delete from activeforums_Templates where TemplateId not in (select MIN (TemplateId)from activeforums_Templates group by title)

update activeforums_Settings set SettingValue=0 where SettingName like '%templateid'

That should hopefully help with your forum as you switch to the new bootstrap theme in ActiveForums