first issue latest nintendont is 375 not 334, update to the lastest one and then try again.
Second nintendont has nothing to do with DM, nintendont uses no mios,no hook no anything, it just uses the ios58 for usb acess and supports sd cards/usb without any cios or anything like that.
Scandisk drive seems to be damaged somehow, when the wii shuts off or the error message pops up it means the usb device wasnt fast enough to keep up with the game requests.
Nintendont does not support splitted games that is for wii wbfs files only, nintendont needs the full 1.35gb isos or the compressed ones but its recomended to use full isos first and foremost for best compat.
Always try botting the games from nintendont directly from homebrew channel, before using an usbloader to confirm everything is ok.