If Quick Check detects errors, and the Repair button reports that it was Unable to Repair all Damage:
1. Run Quick Check again and repair.
2. Go to Menus > Utilities > Data File Tools > Check Data File
(same window as Quick Check)
Click Check Data.
Highlight the suspected file(s) in the left list.
Click Start
Cliock Repair if it reports damage.
3. Repeat #2, Except select ALL Files.
4. Do a Data File Rebuild
This guarantees a data file free of low level corruption.
5. Run diagnostics
Sometimes low level data repair is not able to restore broken data, and thus new errors may show on the diagnostics. In any case, your data file will be in better condition after a full rebuild.
Errors reported on the Data File Tools are usually due to network problems.