Nintendo, I think you have a design flaw. I love everything else about my new 3DS while I was able to use it for a week. But now the microSD card won't stay in so I can't use it. I hope I get a response from them or I am taking a back to the point-of-purchase because the device is useless to me in this state.
I'm really disappointed
**UPDATE**
You can wedge a very small piece of paper between the SD card and the case to keep it in. Have been successfully using it this way for many months.