Crazybird

Hi there, I am new to this and this is my first try mixing audio files. I got 5 copies of a song being mix around in and out and also over laping each other. While I play the song in the program it sounds great!, However, after converting to an audio file, the overlaping part of each song became to much for the file and all i get is static. The other solo part is ok. Only the overlap part where 2 or more songs are mix and played at the same time. And changing the setting to best quality is not helping. The static interfearance sound is still too obvious. Please help!!