What is a copy protected game?
With DS piracy becoming a huge problem, the developers thought of a nifty way to stop pirates from being able to play there games.
Usually this involves infinite loops during game play and non activation of plot advancers.
Currently the only copy protected games i know of are:
Chrono Trigger DS: Endless loop and stuck in church.
Crystal Chronicles - Ring of Fates: Moogle of death that shuts down rom in 20 minutes.
Both of these can be fixed with an updated cheat file.
Get the latest from http://cheats.gbatemp.net/
After replacing the cheat file with the one on your card remember to go into your cards cheat menu and activate the anti piracy cheat.
You can also manually patch if you wish, just make sure to do everything in a new folder as these patches may affect other roms if there in the same folder, also if you use TTDS do not use the chrono patch, runnin a patched chrono trigger from TTDS will create a corrupt save file and corrupt your entire micro sd card.
Chrono Trigger Patch: Download
Crystal Chronicles - Ring of Fates Patch: Download
I will update this post when new games with copy protection show up, and when the cheat files get fixed.