Symantec Messaging Gateway (SMG) installed on a Hyper-V virtual machine is having more than expected time drift. The NTP settings are set up on the SMG.
It is recommended that the Hyper-V Time Syncronization Service for the specific virtual machine be disabled. Only one NTP daemon should be running that will affect the system clock per server.
For instructions on disabling Hyper-V Time Syncronization Service, please refer to Microsoft's Hyper-V documentation.
For more information, see Network Time Protocol (Version 3) Specification, Implemenation, and Analysis at the ITEF website (RFC 1305).