An Arm9 error? You might need to do a
ctrtransfer, as it's usually a sign of system file corruption or something of the sort.
You're not encountering any freezes, random crashes at boot, or on the home menu before launching any app?
What about your installed games, if you have any, can you launch any if them without amy errors?
Also goes without saying that you'd need to check the sd card with
h2testw for errors before doing the ctrtransfer. Backup all the data before doing so Etc.