ntpdate problem in Unixware

Hi Guys,
A weird problem. I have disabled ntpd daemon on a HP server and placed
ntpdate in crontab instead and redirected the log to a file. This command
in cron synchronizes the server with a local time server every 15 minutes.
The weird part is that on 3 specific times (5:00 am, 10:00 am, 15:00 am)
the offset is BIG. 15 seconds for example. Take a look at this log:

19 Jan 14:15:00 ntpdate[25822]: adjust time server 132.147.1.83 offset -0.035859 sec
19 Jan 14:30:00 ntpdate[1251]: adjust time server 132.147.1.83 offset -0.029722 sec
19 Jan 14:45:00 ntpdate[6780]: adjust time server 132.147.1.83 offset -0.038382 sec
19 Jan 15:00:00 ntpdate[12200]: step time server 132.147.1.83 offset -16.724679 sec
19 Jan 15:15:00 ntpdate[17633]: adjust time server 132.147.1.83 offset -0.039956 sec
19 Jan 15:30:00 ntpdate[23085]: adjust time server 132.147.1.83 offset -0.031165 sec
19 Jan 15:45:00 ntpdate[28495]: adjust time server 132.147.1.83 offset -0.038435 sec
19 Jan 16:00:00 ntpdate[4021]: adjust time server 132.147.1.83 offset -0.033537 sec
19 Jan 16:15:00 ntpdate[9448]: adjust time server 132.147.1.83 offset -0.036992 sec
19 Jan 16:30:00 ntpdate[14882]: adjust time server 132.147.1.83 offset -0.044169 sec
19 Jan 16:45:00 ntpdate[20296]: adjust time server 132.147.1.83 offset -0.015335 sec
19 Jan 17:00:00 ntpdate[25708]: adjust time server 132.147.1.83 offset -0.046378 sec
19 Jan 17:15:00 ntpdate[1147]: adjust time server 132.147.1.83 offset -0.029828 sec
19 Jan 17:30:00 ntpdate[6693]: adjust time server 132.147.1.83 offset -0.047750 sec
19 Jan 17:45:00 ntpdate[12113]: adjust time server 132.147.1.83 offset -0.029125 sec
19 Jan 18:00:01 ntpdate[17528]: adjust time server 132.147.1.83 offset -0.022101 sec
19 Jan 18:15:00 ntpdate[22953]: adjust time server 132.147.1.83 offset -0.049704 sec
19 Jan 18:30:00 ntpdate[28377]: adjust time server 132.147.1.83 offset -0.022473 sec
19 Jan 18:45:00 ntpdate[3904]: adjust time server 132.147.1.83 offset -0.042167 sec
19 Jan 19:00:00 ntpdate[9326]: adjust time server 132.147.1.83 offset -0.032394 sec
19 Jan 19:15:00 ntpdate[14756]: adjust time server 132.147.1.83 offset -0.036779 sec
19 Jan 19:30:00 ntpdate[20178]: adjust time server 132.147.1.83 offset -0.029522 sec
19 Jan 19:45:00 ntpdate[25592]: adjust time server 132.147.1.83 offset -0.038430 sec
19 Jan 20:00:00 ntpdate[1003]: step time server 132.147.1.83 offset -16.474113 sec
19 Jan 20:15:00 ntpdate[6586]: adjust time server 132.147.1.83 offset -0.044310 sec
19 Jan 20:30:00 ntpdate[12017]: adjust time server 132.147.1.83 offset -0.029716 sec
19 Jan 20:45:00 ntpdate[17433]: adjust time server 132.147.1.83 offset -0.038163 sec
19 Jan 21:00:00 ntpdate[22841]: adjust time server 132.147.1.83 offset -0.033617 sec

I am really confused. Why
this happens every 5 hours exactly on those times?? Any idea?
I appreciate your help.

Just a thought.
Is there maybe something else in your crontab file that runs at 5:00, 10:00 etc that conflicts with this process?

maybe your server is just doing what the time server is telling it to do...