If host is added to AD, doesnt matter if you configure the NTP or not, it will always sync the time with AD. So it is 30 seconds off, well i am not sure why.
But KB mentioned earlier has this
/etc/likewise/lsassd.conf
change this to no, default is yes (just un comment it)
sync-system-time = no
Have you done this? If not try and set your NTP client again and restart the NTP.
