Event Type: Error Event Source: Windows SharePoint Services 3 Search
Event Category: Gatherer
Event ID: 2424
Description: The update cannot be started because the content sources cannot be accessed. Fix the errors and try the update again. Context: Application 'Search', Catalog 'index file on the search server Search'
Central Administration -> Operations -> Services on server -> Click on the Windows Sharepoint Services Search service and make sure that the 'Service Account' and 'Content Access Account' service account specified are the same. They should not be working with two separate accounts. If it still does not work, Stop the service and while starting it again specify a common service account and create a new Search Database.