Ok so I had bootmii installed on a 2gb SD card. Then I needed the SD card for something else, so I transferred all the files to my computer, used the SD card for the other thing, and then put everything back on.
After doing this Bootmii failed to load up. I got the quick disc tray light flash and it would go to the startup screen. I figured something must have corrupted when I transferred the files, so I formatted the SD card, uninstalled Bootmii and then reinstalled it on the SD card. Still didn't work.
So then I took another SD card and installed Bootmii and it works fine on that card. Also the HBC reads both cards, so I'm not sure why Bootmii won't load up on the first card.
Any ideas? Also sorry if this is confusing, I'm pretty tired.