After deploying the CWA to a front-end server (which also houses OWA for Exchange in my test lab), the front-end service stops on the OCS Server. I receive an error when trying to start it and the event viewer shows an Event ID of 14517 [OCS Protocol Stack].
The server configuration validation mechanism detected some serious problems.
1 errors and 0 warnings were detected.
ERRORS:
Two server roles at FQDN [servername.mydomain.com] have different server version numbers. First server has GUID {8BE9003B-7E63-3A45-85AB-27ABCC61D225} and role 'Communicator Web Access Server' (version 3). Second server has GUID {2EF13F4C-DFFA-8648-9A8F-93FD8EDBC9B3} and role 'Enterprise Edition' (version 2).
WARNINGS:
No warnings
Cause: The configuration is invalid and the server might not behave as expected.
Resolution:
Review and correct the errors listed above. You also wish to review any warnings present.
The next event shows:
The following known servers were recognized on startup:
Server: frontendserver.mydomain.com; UniqueID: {2EF13F4C-DFFA-8648-9A8F-93FD8EDBC9B3}; Role: Enterprise Edition
Server: ocs2007server.mydomain.com; UniqueID: {F8789403-401D-8343-8454-DD555EB0D354}; Role: Enterprise Edition
Server: ocs2007server.mydomain.com; UniqueID: {E2D8F7D1-DB08-2E43-B39D-89D4395630AE}; Role: Conferencing Server; Type: chat; Vendor: Microsoft Corporation
Server: ocs2007server.mydomain.com; UniqueID: {862D193A-497C-D841-B314-74F1E6159213}; Role: Conferencing Server; Type: phone-conf; Vendor: Microsoft Corporation
Server: ocs2007server.mydomain.com; UniqueID: {F7F8A30D-CC01-5D45-9A3C-11BC0E5A5DE3}; Role: Conferencing Server; Type: meeting; Vendor: Microsoft Corporation
Server: ocs2007server.mydomain.com; UniqueID: {F718E2B0-B93C-2341-B2EB-B184E36C2852}; Role: Conferencing Server; Type: audio-video; Vendor: Microsoft Corporation
Server: frontendserver.mydomain.com; UniqueID: {8BE9003B-7E63-3A45-85AB-27ABCC61D225}; Role: Communicator Web Access Server
Then another Error:
Failed starting the protocol stack. The service has to stop
Error code is:0xC3E93C47 (No Message Text Found).
Cause: Check the previous entries in the event log for the failure reason.
Resolution:
Try restarting the server after resolving the failures listed in the previous event log entries.
As soon as I remove the CWA from the front-end server, the service will start up just fine. I've tried looking all over the registry for any reference to a previous version but I can't seem to find anything. 
