Thanks Thor.
So I found a load of stuff stored in ProgramData\Steinberg. Whilst there was ‘User’ read/execute access to much of this, there were some files without this permission. So using admin rights, I changed the permissions for the Steinberg directory for users to allow this permission and set it to ripple through the directory structure and for new files to inherit the same permission.
And it worked!
Most strange that some areas had access and others didn’t, but hopefully fixed for the future now. Still don’t know why Cubase referred to wav samples under a “vstsound:\\” address.
Thanks,
PMR.