I have a Windows 2003 domain with two domain controllers. All of the domain members have the W32Time event 27 in the system logs. (The response received from domain controller is missing the signature. The response may have been tampered with and will be ignored.)
Now, I would typically do all the w32tm /resync, /setsntp, etc tricks, but this is happening to ALL domain members, so there must be another global issue. In addition, those fixes do not stick with the servers I've tried them on. I feel like this is a PDC or Group Policy issue, though registry settings on the PDC look OK, and there does not seem to be a GP in place which affects time.