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 is using some incorrect terminology as looking up "empty MBR entry" shows only the one result I mentioned earlier.

Anyone know how to fix this?

 

In fact, formatting the SD card through GM9 does actually make it work on the DSi. The problem is that my computer then doesn't recognise it for whatever reason. I noticed the GM9 formatting leaves 4 MB of unused space BEFORE the 948,50 MB fat32 partition, perhaps this is why. What a mess!

 

...and of course, after turning my computer off and on again, the SD card is now formatted and recognised correctly, and the problem is solved. Hopefully others who run into this error will be able to solve it the same way.