I only have one version of Cubase on this machine. I have uninstalled Cubase and trashed all the folders in (%appdata%/Steinberg) and start fresh.
I am thinking it must be the copy protection that is the causing the issue. The light goes off the dongle or freezes on the dongle.
Scanning the elicencer sometimes can be a problem scanning. I know Steinberg has always been heavy handed with the elicencer.