iVMS-4200 (storage server) interfering with windows time

I have been using iVMS-4200 software for a bit over a week. I have 2 Hikvision cameras (2332, 2032) connected to a Netgear 8 port (4 are POE) switch which then goes to a 4 port wireless router (Linksys EA2700) that is connected to the PC. I run iVMS-4200 (storage server) software on this PC. This PC is at a remote location.

On another PC, I run the iVMS-4200 client - connecting to the camera and the remote storage server. This connection is wireless (with good signal strength and high connection speed). Both PCs run windows 7 professional.

I want the cameras and the 2 PCs to have accurate time. I know there is time correction in windows 7, but it is rudimentary. So I installed (meinberg) http://www.meinbergglobal.com/english/sw/ntp.htm NTP for windows.

On the client PC - everything went well, NTP converged in a few minutes. But on the PC running the iVMS-4200 storage server, NTP never converged - even after 10 hrs. The offset reported was as large as 1.5 seconds. Whereas on the client PC, the offset was in the 10 millisec range. (Both PCs getting time from the same NTP server.)

Then I stopped the storage server, and NTP converged within a few minutes with the time offset in the 10 ms range. Restart the storage server and the NTP time offset goes erratic (300-1300 ms jumping wildly).

(Note: In the iVMS-4200 storage server software, I left the System -> Time -> NTP box -> unchecked).

So I uninstalled NTP, and re-enabled the windows (7 built in) time service. Same behavior: With no iVMS-4200 storage server, time is well behaved (matches the other PC with a slow drift). Run the storage server, and the time gets offset by random amounts. (We are only talking about fractions of a second - getting as high as 1.5 seconds for the hour period I observed it. So there are workarounds - like using ntpdate to set the time periodically, or just living with the error if it stays bounded).

I conclude that the iVMS-4200 storage server is somehow causing the PC system time to become corrupted. This behavior can be observed within 5 min of starting the storage server.

Thoughts?

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(Note: In the iVMS-4200 storage server software, I left the System -> Time -> NTP box -> unchecked).

....

SOLVED

It turns out the "NTP sync to time.windows.com" checkbox on the storage server WAS checked.

I was controlling this via the client menu, and on the server page, but had a camera highlighted instead of the storage server. So I accidentally was disabling NTP on the camera, but not on the storage server. So periodically the storage server was resetting the system time bothering the NTP software I installed in windows.

Once I unchecked this box, NTP converges quickly.