Looking for a NTP Server Software for Windows

I'm looking for a preferably free NTP Server for Windows Server 2003/2008. We have already tried the built in Windows Time Server, but our tests did show that it is not very accurate, we see time differences up to 500ms. The max time difference we can allow for our application is ~100ms.

Now we have already used the Meinberg NTPd for Windows (http://www.meinberg.de/english/sw/index.htm). It works great except we have one big issue with it: If there is a network connection problem betweek client and server, the ntp server is in a panic state, it won't give the client a new time until we restart the ntp service. This is a big issue which has caused us some trouble. It was working fine for months until there was a network problem we didn't notice, we only noticed it after a week when the time difference was already 30 sec. on the clients.

So please suggest some alternative NTP Server for windows. I did Google but I get alot of unrelated search results.

Thanks in advance!

Edit: So far the ntpd windows version was very accurate and I'd like to stick with it. The only problem is the "panic state" after a network disconnect. Maybe some knows here what the cause of this is and how to fix it. Also, I forgot to mention that we have a server/client setup like this:

Server1 --> Server2 --> Server3 --> Client1 --> Client2 --> Client3

So Server2 gets its time from Server1, Server3 gets its time from Server2, and the Clients get their time from Server3. Also, there are clients connected directly to Server2. It is important that all Servers and Clients have the exact same time (within ~100ms)

Now there was a network problem with Server3 and its clients. The servers run the ntpd port for Windows, which acts as NTP server and client. The clients have Dimension4 as NTP client. After the network problem, the error message in D4 was something like this (out the top of my head, don't have the exact error message):

Server response: The server is in a panic state (could not sync clock)

I read through the ntpd docs, and the only mention of "panic" is when the time difference is 10000 seconds which will cause to exit the ntpd server but this was not the case. Also there is a "-g" command line switch to disable the panic exit, but it is already set by default.

Any ideas what could cause the panic state and how to get rid of it next time?

From serverfault Simon

• I am using NetTime, from many years, both as client and server.

  This software is primary a NTP client, but it works well also as NTP server within a LAN (option: allow other computer to sync to this computer).

  Simon : Thanks alot! I'm going to try it and report back

  Simon : I did try it in our test enviroment, and I have 2 problems with NetTime: The accuracy is similar to the windows w32time service, so I get difference of up to 500 ms, secondly, we use Dimension4 on our clients to get the time on the clients, and they fail to sync with NetTime because if an "invalid stratum", from what I read, NetTime registers itself with a stratum of 16

  lg : Sorry, I never needed this accurancy, so I didn' know these problems.
  From lg