In case you want to try the reset, Before performing the reset, you can make a backup of all your data so as not to lose the data. then just restore the backup.
Also, we, the owners of the CTX 3000/5000 are experiencing problems with some tones, waiting for CASIO support to release the firmware update 1.08 which, apparently, corrects some of these problems, the version of your keyboard is updated at least to version 1.07?