After installing the Office Communications Server 2007 (OCS), if your users get an Address book synchronization error, it is probably because they are not able to access the Address Book shared folder that you created during the OCS setup.
Make sure you have verified the configuration as per KB938286.
On the client machine, try to browse the location https://<OCS POOL FQDN>/Abs/Int/Handler. Take care to use the OCS Pool FQDN and not the server FQDN or IP address. Make sure that your browser does not report any certificate errors. If it does, then you need to sort out the problem.
- If the root CA certificate is not installed on the client machine, install it.
- If the common name of the certificate is not the OCS server FQDN, you need to re-issue the certificate so that it contains your OCS Pool FQDN. This can be done by running OCS Setup and selecting the option to issue a certificate. Make sure you apply the certificate.
Once you have ironed out all the certificate errors, you should no longer get any certificate errors on IE when you navigate to the above URL. Sign out and sign in to Communicator 2007. You should be able to search the Address Book and the exclamation mark on the OCS icon should vanish.