Mp 4 my songs are being cut.

well i posted before but it didtn really help as much so i think i should include more detail? Well everytime i want to hear my songs on my Mp 4 they do come on but they are being cut. I chekaed online to see how many songs it can take up to but my mp4 is 2 gb so around 500 the other day i dont kno it was fine but then all of the sudden it jus cuts the songs short to about 10-15 seconds but i did equalise one song over and over again and that played fine but when i didnt equalise it, the song stil cut off. And i cant keep on equalising a song like 50 times just so that it doesnt turn off or skip to the other song. Any ideas or resolutions. My Mp4 player is Digital mp4 player Aura company.