Originally, we were having an issue where Outlook 2003 clients would throw "Task 'Microsoft Exchange Server' reported error (0x8004010F): "The operation failed. An object could not be found." when attempting to send/receive. I tracked the issue down to the OAB after a short Google search.
Our OAB virtual directory was actually empty, and there was no GUID folder before I found the solution below.
When attempting to download the OAB directly from Exchange 2010, one would receive the message: "An error occurred while opening the Microsoft Exchange Offline Address Book files," and event ID 27 (source: Outlook), "The operation failed," would be recorded in the application event log.
This post provided the solution. After running the command in Exchange Management Console on the 2010 server:
I was able to download the OAB successfully from Outlook 2010.