There was a an update issues to the StreetPass Plaza application today, allowing European 3DS owners to download and purchase four new paid downloadable games (see today’s other post!).
Unfortunately, this also caused a number of 3DS owners’ systems to crash when trying to purchase one of the games. The crash may happen at different points in the process—entering the store, at PoP, or elsewhere—which means that Nintendo’s servers are likely the issue here.
Nintendo has been made aware of the problem and are working on a solution. If you were planning to purchase one of these games and experience a crash, give it a few hours—it probably won’t be too long before the application is back on its feet.