I followed this guide HERE and used USB Loader GX for a couple of months without any problem. I played both Mario Kart and Mario Galaxy with no problem.
Then I got Smash Bros. and couldn't load it onto my HDD, so I followed this guide HERE.
Now I can't play Mario Kart or Mario Galaxy. I'm guessing I messed something up an IOS that is particular to Mario Kart or Mario Galaxy.
SSBB is a known issue. Prior to the release of IOS 249 Rev 17, it'd not work correctly. It has to use Rev 17 of that or Hermes IOS 222. These versions support dual layered media. You took a left when a right was called for, sorry. Also realize that if USB gaming as well, you shouldn't even install it til you have that version and IOS on your Wii. We never encourage mixing and matching of mods/tutorials (at least they're both wiihacks). The one you followed is user-submitted; might want to ask that user about this first as I don't even wanna guess what went wrong.
just my opinion:
I had issues also with USB Loader GX not recognizing games one day and recognizing two days later for no reason!!!
I went to Wiiflow, works like a charm.
Mind you I still use USB Loader GX to copy games to my WFSB drive as it tells you the new compresses size....
that's my 2 cents.