I have a funny story to tell. So on sunday I see the big news that DIOS MIOS has been released. I fire up my wii, turn on wiiXplorer and get FTP running. Back on PC, I download DIOS MIOS v2 wad, updates for USB Loader GX, and (I thought) wiiflow. I send the wad to my wad folder on my sd card and all the apps to their appropriate places. Turn off the wii, remove my HDD and start loading games on it. The first game I try loads up just fine, and I think "great, it works". Load up other games, and I notice they aren't showing up in wiiflow at all, and only in USB Loader GX. Turns out, both were still set to point to SD card. So I fix that, move data around to make sure everything is on the HDD. Now only USB Loader GX is seeing the games on the HDD, but every time I launch I get black screen. No joy. No splash. Nothing. So I'm thinking my HDD is incompatible, but I'm going to try a few more steps to see.
First thing I do is move everything off the HDD and reformat with 32k clusters. I had verified previously that it was already formatted this way, but I wanted to be absolutely sure. Formatted everything, moved everything back over, still no joy. So then I think "maybe I need to overwrite dml (which I had) with the original mios v10 first". So I go to DOP-ios thinking I can get miosv10 there (but I can't). So having no luck then, I say "what the heck, I'll try reinstalling DIOS MIOS v2 over again". I get into Wad Manager, and the music starts up, and I realize that I hadn't ever installed the wad IN THE FIRST PLACE.
Installed DIOS MIOS. Plugged in HDD. Fired up mario sunshine, and I got a black screen. I curse, switch back to baseball, and do more thinking. After we lose the baseball game, I switch back to wii to find that mario sunshine had indeed booted just fine. Tested my other 3 games, they all booted fine, with a splash screen. Put all my games on there, have joy finally.
Moral of the story: if you're having trouble getting DIOS MIOS working, the first thing you should do is install DIOS MIOS.
I'm a moron.