Due to changes in the way Windows Vista and Windows 7 update the system time, the API SetSystemTimeAdjustment() will lose time adjustments that are less than 16. The time adjustment represents the number of 100-nanosecond units added to the system time-of-day for each lpTimeIncrement period of time that actually passes.
This is a known problem with the Windows versions specified in the Applies To section. Time adjustments of 16 or greater still work as expected.
clock syncronize GetSystemTimeAdjustment