You may encounter this error in the Application Event Log after installing MSS(E) in your farm:
Event Type: Error Event Source: Office SharePoint Server Event Category: Office Server Shared Services Event ID: 6482 Date: 5/4/2009 Time: 11:00:49 AM User: N/A Computer: SEARCHSERVER Description: Application Server Administration job failed for service instance Microsoft.Office.Server.Search.Administration.SearchServiceInstance (b2ef3361-3f34-41e4-8e2a-56cbd5fc78f4). Reason: Access to the path 'C:\WINDOWS\system32\drivers\etc\HOSTS' is denied. Technical Support Details: System.UnauthorizedAccessException: Access to the path 'C:\WINDOWS\system32\drivers\etc\HOSTS' is denied.
For what ever reason, Microsoft wanted Search Server to edit the HOSTS file on the MSS(E) server. In order to resolve this error, provide the WPG_ADMIN group with Modify NTFS permissions to the %windir%\System32\drivers\etc directory. If you restart the Search Server service, the error should not appear after making that modification.