Sound problems

[Hypnotic]

A couple days ago I was trying to set different notification sounds for emails and txt messages in which I succeded in doing.

A couple days later the phone would start to force close and said it had no default ringtone or notification sound and I determined that whenever it was rebooting it was due to the fact that it was not able to play these files or something. In the end I had to do a factory reset on the phone and clear my SD card.

Does anyone know what could have caused this?