"The search application <GUID> on server <servername> did not finish loading. View the event logs on the affected server for more information."
Additionally the following event is present in the Application Event Log:
Log Name: Application
Source: Microsoft-SharePoint Products-SharePoint Server Search
Event ID: 25
Task Category: Gatherer
The application cannot be initialized.
Application '<Search Service Application>'
Access is denied. (0x80070005)
Check the system event log for group policy changes that may have occurred around the same time as the search errors. Determine if any group policies have altered permissions on 'WSS_WPG', or WSS_ADMIN_WPG groups
Log Name: System
Event ID: 1502
Run the Psconfig command-line tool for SharePoint Products as follows:
Psconfig -cmd secureresources
Note: To run Psconfig at a command prompt, navigate to the '%COMMONPROGRAMFILES%\Microsoft Shared\web server extensions\14\bin' folder
For more information about Psconfig, see Psconfig command-line reference (SharePoint Server 2010)