COBRT006 Index structure corrupt (Recoverable)

The index of your data file has become corrupt, and although it still may be accessible, you should rebuild it.

Resolution:

Use the Rebuild utility to rebuild the corrupt index. Use the options /d and /e when rebuilding the file; for example:
rebuild filename1,filename2 /d /e
and then rename filename2 to filename1.
Note: Other rebuild parameters may be required, depending on your data file.