As promised, here is the resolution for this problem:

1. SP4 was installed on the offending server;

2. DBCC CHECKDB and DBCC CHECKTABLE now showing the same error; that is, the message returned from the DBCC commands were now consistent;

3. Offending table now identified;

4. Set database to single-user mode;

5. Executing DBCC CHECKTABLE with the various REPAIR options did not fix the problem;

6. Drop all indexes and constraints on the table;

7. Rerun DBCC CHECKTABLE with REPAIR FAST option - no error message 🙂

8. Identify and remove offending duplicate records;

9. Re-apply all indexes and constraints;

10. rerun DBCC CHECKTABLE;

11. Reset database to multi-user mode;

HTH

Paul