I've got a WII with a Wasabi DX and USB loader GX.
When i'm playing a game my Wii crashes, I need to unplug the power cord to start my Wii again.
I dont have this problem when I play an origional game.
what drive are you using ?
USB drives have a nasty habit of spinning down during game play causing this, you should use the software that came with the drive to tell the drive to never spin down.