800706ba error on cluster validation

I'm getting the dreaded error below on 2 vsphere 6 Windows 2012 R2 guests:

"There was an error creating the server side agent (CPrepSrv).

Creating an instance of the COM component with CLSID {E1568352-586D-43E4-933F-8E6DC4DE317A} from the IClassFactory failed due to the following error: 800706ba The RPC server is unavailable. (Exception from HRESULT: 0x800706BA)."

I see a lot of references to improper sysprepping and matching SIDs, but I'm pretty sure I sysprepped the original image as I should have. I had no trouble joining both to AD on the same subnet, and the computer objects have different SIDs (one number apart). Does anyone know of anything else I can check?

Thanks.