This problem has already been resolved (just sharing info)
Patch Manager Computers and groups \"All Computers" (list) displays incorrect Operating system version for W2K12 servers. Some of the W2K12 servers show up as W2K3 and W2K. Yet, in Managed Computers the OS appears to be correct. This would be trivial normally, but these server have intermittent problems getting windows updates. I have tried troubleshooting inventory, deletion, certificates, etc.
This problem was resolved by installing the update \ hotfix below.
An update for Windows Server Update Services 3.0 Service Pack 2 is available (KB2734608)