Unlaunch error: empty MBR entry

I get this error whenever I try to start my DSi with the SD card inserted. Without, it works fine and shows the Unlaunch UI. I found one other person who also encountered this problem and their final post was a variation on the ever useful "fixed it nvm".

I've tried formatting the SD card on my computer, deleting the filesystem, recreating it, using different filesystems, and also tried formatting through GM9 on the 3DS, but still it keeps on telling me "empty MBR entry". I suppose Unlaunch...

Unlaunch error: empty MBR entry