> It means you're using an old format CHD with a 'u' update of MAME. You can
> Google for CHDMAN, and once you have it, would need to go into the folder of the
> CHD that needs updating. Then you'll have to go to a command line prompt, and
> cd (change directory) to that ROM folder. Then when there, type:
>
> chdman -update chdname.chd chdnamenew.chd
>
> Then you can exit (type "exit") from the command line back to Windows, delete
> the old file and rename the new one. Then it should verify. :)
>
Great that U.