I'm looking into this to find out for certain what mechanism we're using to determine this.
Right now I am guessing it's probably based on a value in 'InstallationType' key (or possibly a combination of keys) within HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion.
However, I'll let you know for certain what I find out from our engineering team.
So what I've been told is that we are making an API call to NetServerGetInfo().
Unfortunately I'm not certain of the exact spots this function is pulling information from and the Microsoft documentation doesn't really explain well. I would be guessing that it's based on information in the registry or a comination of registry and something found in system files.
If you want, it might be a good idea to open a case so we can take a look through logs from scanning the machines where you see such an issue. Maybe we can help you pick out what would be causing this. 1-866-407-5279 or https://support.shavlik.com/