Hi, I've just hacked my Wii and I experience the same issue.
I did everything according to mobclutch's tutorial from reddit
https://sites.google.com/site/completesg/hacking-guide
And configured the usb flash with this tutorial which is also based on mobclutch
After uploading my games to USBHDD i couldn't launch them (black sreen).
Then I fumbled in usb loader gx game setting and changed the video to NTSC, as in the Wii Backup Manager, but every second launch the USB Initialization freezed. (USB loader gx, latest version R1263
I used this tutorial with solution I advise you.
https://www.reddit.com/r/WiiHacks/comments/2z1ei5/usb_loader_gx_freezes_or_hangs_at_initialize_usb/
It worked the first time, but again, games do not launch even with NTSC option checked.
I restarted by wii and again, it freezes on USB initialization.
I'll try with channel forwarding and let you know if it changes anything.