This informational message indicates that the index cannot be checked because one of the filegroup IDs that is stored in the metadata of the index does not exist. The filegroup ID that is not valid might pertain to the data itself, or to the large object (LOB) data, or to the row-overflow data.
If there are no problems, all other indexes of the same object will be checked.
Look for Hardware Failure
Run hardware diagnostics and correct any problems. Also examine the Microsoft Windows system and application logs and the SQL Server error log to see whether the error occurred as the result of hardware failure. Fix any hardware-related problems that are contained in the logs.
If you have persistent data corruption problems, try to swap out different hardware components to isolate the problem. Check to make sure that the system does not have write-caching enabled on the disk controller. If you suspect write-caching to be the problem, contact your hardware vendor.
Finally, you might find it useful to switch to a new hardware system. This switch may include reformatting the disk drives and reinstalling the operating system.
Restore from Backup
If the problem is not hardware related and a known clean backup is available, restore the database from the backup.
Run DBCC CHECKDB
Not applicable. This error cannot be repaired automatically.