My USB HDD Drive[NTSC] copy of Ben 10 Vigilax Attacks will run but I need to hit the 'B' button to skip through the 'Cartoon Network' intro splash screen otherwise it freezes as it loads. Once past that point seems to work fine.
External HDD - Iomega Select 500 Gb Portable (USB powered) - split approx. 170/10/320 NTSC/FAT32/WBFS [I set it up before usbloader was FAT/NTSC compatable :-)]
Wii [American NTSC] 4.1U - soft modded cIOS 249/250 rev 14, Hermes 222/223
Prii-loader 0.29 region free hacks enabled, update blocking is enabled for system and games
BootMii as IOS
USBLoader latest stable release 874 (as per internal wifi update).
Video Mode - Disc Default
VIDTV - OFF
Game Lang. - Console Default
Ocarina - OFF
IOS -IOS 249
Error 002 fix - Anti or Yes
Patch Country Settings - OFF
Alternate DOL - Default
Block IOS Reload - OFF
So basically what I'm saying is there is hope for your son.