You are right. if you don't see game icon, it's probably a bad ISO. try another ISO.
If you want to use nintendont with 1TB HDD, you need to format (and delete everything !) to FAT32.
if you have important files on HDD, make a copy to your PC first because formatting to FAT32 will remove all files.
FAT32 is better for homebrew, you can use the same HDD for all homebrew, no need to change device every time.
You can also use USBLoaderGX to launch gamecube games with nintendont, and have different game settings.
If you have files bigger than 4GB you can't copy to FAT32 ! Wii game is not a problem, but if you have other file like Videos or HD Movie you can't copy to HDD ! so, if you need big file to HDD don't format to FAT32.
If you want to format to FAT32 :
- copy all file to PC (backup !)
- format the partition with this :
http://www.ridgecrop.demon.co.uk/index.htm?guiformat.htm
(PC can't format 1TB FAT32, you need the guiformat program)
choose
- quick format
- 32k/cluster if you can
After format:
- restore backup file from PC to HDD (copy back old file to hdd)
- put gamecube games to HDD too (copy /games/ folder from lash drive to HDD)
- USBLoaderGX should work directly with nintendont (you need to display gamecube games > top menu > 4th icon > gamecube)