While comparing the files I have in my mod folders with the base files in the 4.0 beta, I discovered that I had a copy of StarbaseModuleDefs.xml that attempted to fix a bug in 3.96, that apparently has not been fixed in 4.0.

The CulturalForumModule has:

    <Prerequ>
      <Techs>
        <Option>CulturalExchange</Option>
      </Techs>
      <StarbaseModule>CultureRingModule</StarbaseModule>
    </Prerequ>

Which I think should be:

    <Prerequ>
      <Techs>
        <Option>CulturalInfluence</Option>
      </Techs>
      <StarbaseModule>CultureRingModule</StarbaseModule>
    </Prerequ>

i.e. CulturalInfluence instead of CulturalExchange.

If I'm right, please add this to 4.0.  If I'm wrong, please let me know so that I delete that from my mod folder.