Same problem here, haven't found any solution
Please excuse my poor english. I'm a spanish speaker.
I have the same problem:
I have a d2PRO chip installed. No problem at all playing Wii Backups.
Most GC backups runs well also. But I'm getting DRES with a lot of games, precisely those who need Audiofix.
I have updated my D2PRO firmware, running Utility Disk 1.7. Audiofix option is ON. I have proved de-activating It, seems to be Ok with some of those games, now I'm able to play them, but I'm still getting DRE'S (An error has occurred.. please turn off and refer to the nintendo Gamecube booklet etc etc) in many of them (Eternal Darkness, Ikaruga, and so on).
I ran fstfix patching the audio, with no results.
I'n running out of ideas, I made a lot of googling about this.
Anyone can help?
Best regards from Chile.