Event ID: 4126
Event Type: Error
Event Source: Ci
Event Category: CI Service
Description: Cleaning up corrupt content index metadata on c:\system volume information\catalog.wci. Index will  be automatically restored by refiltering all documents.

Resolution:

• Go to: Computer Management > Services > Stop [Indexing Service]
• Manually delete: System Volume Information > catalog.wci
• Go to: Computer Management > Services > Start [Indexing Service]
• Restart the machine