This is on a hp desktop that has been in service for a few years. Where can I find the label that is used to identify the os. Also what is the file that contains the list of supported os's.

C:\>zac reg

Processing Command: reg

user name: admin
password: ******

Unable to register with the server at:
Service Error. code: -21, message: Could not determine device type from <OS>
tag: unsupported