Okay, I have a DSi XL, at the latest 1.4U firmware. So when I insert my DSTWO while in the DSi Menu and start it, I get the black screen stating "An error has occured" and other stuff. Although if I soft-reset the DSi from there and start the DSTWO, it boots up just fine. I thought this was an issue with the firmware, so I flashed the DSTWO's firmware to 1.05, and it didn't change anything. On a related note, if I insert the DSTWO while the DSi XL is off, it boots up just fine. I'm wondering, what's causing the problem? Also, the black error screen pops up every time when there's no microSD card inserted. I'm kinda surprised that there's no built-in error screen.