firewire drive error

[Jan Melichar]

What I feared from time to time has happened. I cannot access one of my 
firewire which, as is the way with large drives has files on it which 
have not been backed up. 'You have inserted s disk containing no volume 
  that Max OX can read....' Plugging it into may portable, using a 
different cable has made  no difference. Disk Utility reports 
'Catalogue file entry not found for extent' HELP

Can anyone suggest a remedy?

Jan