I’ve a theory as to what might cause this. It has to do with CuBase Media Browser scanning various folders for potential content. The short version is, if you’ve still got installers and such lingering on your system in a location that MediaBay keeps scanned for possible content (Cubase itself can ‘mount’ VSTsound files, so samples and such can be drug right onto tracks if they are not contained in ‘locked’ layers), then the HALion engine goes fishing for USB licenses in an attempt to make the VSTsound container’s contents available for use in Cubase.
Have a look at this thread about the theory, my personal related experience, and how I solved it here on my system: