5 way's that freeze your ps3 error data (corrupt files),overheating (thermal paste dry out or dust),HDD getting to his end. (mostley you can hear a tik when it's running) and last wrong debug settings.
So try first recovery mode rebuild data,look all your debug functions are correct,check your harddrive,open ps3 remove all dust clean parts and set new thermal paste by cooling plates.
rebuild ps3