If you want to check your logbook for errors, Not only DXCC enity errors, But almost all sorts of errors in your log, Then you should make yourself a Clublog account, Its fast and easy. These guys have made a really good tool to help you out. After making an account, Upload your log in adif format, And you will recive a report via your email. Then fix the errors in your logbook if you got some. Its also a great tool for dxcc statistics, Band/mode/overall and OQRS etc.
Intro to Club Log:
Why not check it out: