For more information about this event see TD941846
(Event ID 1220 - LDAP over SSL appears in the Event Log).
This is caused when you do not have a local Server Certificate on the Windows 2003 CA. You need to attach to the CA server with the web page, which should be http://<yourserver name>/certsrv .
Then you need to select request certificate, create a customer certificate request, fill out data, select Server Authentication Certificate for certificate type needed, and make sure you selected Store certificate in the local computer store, then submit it. Now, depending upon your CA server settings, you will either receive the certificate, which you then need to click Install this Certificate and you are good to go, LDP will connect locally and you will have a message in the event log telling you SSL is now available. On the other hand, if you are not auto issuing, you will need to go into the Certification Authority tool and ok the pending request, than go back to the webpage and install it.
for details on this event.