During my demo environment installation (OCS and Exchange 2007), I got a few blockers that I couldn't find documented on the Internet. Maybe, it could be of your help. Here they are:
Failure [0xC3EC7924] Schema definition for the requested Active Directory attribute isn't available. Please ensure local ADSI schema cache is up-to-date.
This problem occurred during the Deployment step of the OCS installation. Every AD schema preparation step ran successfully prior to this one. Checking the logs, it turns out that the AD schema class "Phone Route Usages" doesn't exist or there's a problem reaching it. The solution was to delete the schema cache file on the local server. The schema cache file is stored under C:\Windows\SchCache and this is used by ADSI to avoid the roundtrips to download the schema for every AD request. Simply delete the files stored in this folder (every domain has its own schema cache file) and re-run the installer.
There was a problem verifying the certificate from the server. Please contact your system administrator.
This problem occurred during the first logon with Office Communicator 2007. The resolution was to go to the server, start mmc, open the Certificates snap-in (computer account and local computer), find the root certificate (the issuer of the certificate used by OCS - VeriSign or your organization's KDC), export it to a file, and import it on the workstation. Don't accept the automatically determined location when importing the certificate on the client. Choose the folder yourself, it has to be the "Trusted Root Certification Authorities".
Presence icons didn't appear on the SharePoint site:
Error: Opening package 'Z:\Exchange 2007\Setup\ServerRoles\UnifiedMessaging\umlang-en-US.msi' failed. This installation is forbidden by system policy. Contact your system administrator. Error code is 1625.
I got this one when tried to install the Unified Messaging Role for Exchange 2007. I tried to run the installer package from the network (mapped drive) which was forbidden by System Policy. So, copied it to the local disk.
The Unified Messaging server has encountered an argument that is missing or not valid: "AttachmentName".
I got this error message to the event log. I tried to create a fake voicemail message for the Unified Messaging service on Exchange 2007 by copying a WAV and TXT file to the UnifiedMessaging\Voicemail folder on the server. The TXT file is a descriptor that contains a link to the WAV file (the actual voicemail message). I dropped these 2 files together to the same folder, but it seems that the TXT file got there first and when UM got notified about the new file, it tried to open the WAV file which was not yet there. The resolution was to copy the WAV file first, and *THEN* the TXT (has to be very fast).
Free/Busy lookup was not working from Outlook
When tried to look up other user's F/B information, Outlook showed me a grey line (no information) for them. Enabled Outlook logging and the following error message was logged to the log file:
2007/08/27 14:29:57.431: Getting ASURL
2007/08/27 14:30:10.589: Failed to get ASURL. Error 8004010F
Checked with MfcMapi that the SCHEDULE+ FREE BUSY folder was accessible and it was populated with every mailbox. Then, asked some more clever guys and they told me that in order for F/B to work, AutoDiscovery also has to work. I could check how AutoDiscovery works by holding the Ctrl key and right-clicking on the Outlook icon in the system tray area and selecting the "Test E-mail Autoconfiguration" menu. From the dialog, I cleared the Guessmart and Secure Guessmart checkboxes, typed the email address and password of the current user and ran the test. It turns out that I needed another DNS entry with a name of autodiscover.yourCompany.com. Outlook then calls this host on SSL and tries to retrieve a file called autodiscover.xml to retrieve AutoDiscovery information. You can check if this request works: https://autodiscover.yourCompany.com/autodiscovery.xml - if it does, then try again and OOF will work now.