Click Start, click Run, type regedit, and then click OK. In Registry Editor, locate and then click the following registry key:
Right-click MSV1_0, point to New, and then click Multi-String Value.
Type BackConnectionHostNames, and then press ENTER.
Right-click BackConnectionHostNames, and then click Modify.
In the Value data box, type the URL mentioned in the above warning event, and then click OK.
Quit Registry Editor, and then reboot.
From a support forum: This settings should fix it:
The server must be restarted for the settings to take effect. See ME896861
for details about these registry settings.
If you installed a Office communication Server 2007 R2 Front-End server and see this event then when your Server gets refered with your OCS Pool name and this SPN is not assigned to this server we get above mentioned event from LsaSrv. To resolve this we simply need to add one spn for your Front-end server as following and you should be good.
setspn -a RestrictedKrbHost/<FQDN_OCS_Pool_Name> <Front_End_Server>