Hi HillBelly,

Have you contacted Tech Support?
https://www.maxon.net/en/support-center
I'm not supposed to provide what tech support is for, to keep things in the correct information flow.

Anyway, perhaps go to Preferences> Render> Redshift, and switch User Interface>Material Preview to Off (or When Render is Idle).
I suggest testing if the problem persists when you use a different drive, perhaps just a fast UBS.

Is that the same problem on a different computer for you if you can?

My best wishes