Here, I got this off of Nintendo's website. It could be possible it just needs a restart
Press and hold the POWER Button down until the system powers off (about 10 seconds), then power the system back on.
General system stability can be improved by applying the latest system update. Try applying the latest system update and see if the issue improves. How to
If the system only freezes when using a specific game or application downloaded from the eShop, check the eShop for an update. How to. If the update was already installed, delete and redownload it.
If the game was downloaded, use the Nintendo 3DS Download Repair Tool to check the game or application for errors and repair if necessary. How to