So far I can tell there is no one else. I hesitate to tell to reinstall, but it seems very plausible this time.
Anyway, we are not supposed to give technical support here, this needs to be done by the support directly. So all the flow of follow up information is perfect and guarantees a good and complete source for the developers.
All I might can share, so you have already some information for the support: You can check your R20 folder if in the “corelibs” both volume files are installed. Perhaps run a disk diagnostic as well. Again, I can’t do more here.
All the best