I was having the same problem. So between MAC swaps I would shut down the 3DS. I get a streetpass hit within seconds of it saying that the Nintendo Zone is available after it boots back up.
Also delete any wifi connections that you may have for your normal internet. That also seemed to screw...
@Xdqwerty, to answer your question, they're a fusion Brit-pop/J-pop/electronic band with a woman vocalist. Flamingo is hands down their best known song but they've got a ton of other really good songs