When trying to enable the Office SharePoint Server Publishing Infrastructure feature we were getting an “Access Denied” error.  The error in the application event log was:

Event Type:    Error
Event Source:    Office SharePoint Server
Event Category:    Publishing Provisioning
Event ID:    4965
Date:        5/13/2009
Time:        10:16:31 AM
User:        N/A
Computer:    SERVERNAME
Description:
Event log message was: ‘Failed to provision the scheduling job definitions.  Page scheduling will not succeed.’. Exception was: ‘System.Security.SecurityException: Access denied.
…

To resolve the issue, we took the following steps:

1. Used stsadm to activate the feature:
   1. stsadm -o activatefeature -name PublishingResources -url http://www.example.com
2. Clicked the [Activate] button on the Site Collection Features page.