Machines with corporate Windows licenses are sold to companies to be used by employees; if the machine was (legitimately or otherwise) re-sold to a person outside the company, the machinbe may not be able to reach the internal company activation server, and thus the license may no longer be valid, which would explain the failure of activation. Alternatively, the Windows install may have been from an Enterprise disk and falsely activated by a invalid key which has now been detected and deactivated (this often happens with Windows updates.). You could try rolling back to Windows 7 to see what happens.
