ntpd strange problem

[Wojciech Puchar]

>> 0x2041: Clock Unsynchronized
>> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
> It will take 5-10 minutes for ntpd to synchronise to its upstream servers.
> Until then, the clock will report that it's unsynchronised.  If "ntptime"
> is still reporting that it's unsynchronised after a long period, you will
> need to do more troubleshooting.

yes the problem is that:

after starting ntpd time is exactly fine

ntpd_sync_on_start=YES
ntpd_enable=YES


but then while ntpd works, time seems to get out of sync to the extent of 
normal RTC imprecission - in order of few seconds per day.

ntpd seems like not to update time properly.

restarting ntpd fixes time again.

what should i look at to find a source of problem