C++ :: System For Managing Radio Station - Crashes When Tries To Dereference The Iterator

My assignment is to write a system for managing a radio station. The code is composed of four classes:

Song: each song has a name, a composer and a singer, and has a few segments: INTRO,VERSE,CHORUS,TRANSITION, while each represents a different length string of chars.
Playlist: a multiset of songs, and a pointer to a RadioStatistics instance (see below).
RadioStation: a set of Songs (will represent the station database), and a list of Playlists, each playlist holds a few songs from the database.
RadioStatistics: can only be instantiate once, this object gather statistics; it has two maps: one that counts how many times a song was played, and second that counts how many times each singer was played. (the key is the song/singer name, and the value is the counter).

The RadioStation has a constant that defines a limit to how many times a song is allowed to be played. whenever a song reaches this limit (meaning, it was played too much), the program needs to skip to the next song in the database.

so, I run this test from main, and the program crashes (or more accuratly get stuck, since the console stays open and the program keeps working until I stop it).

I made a few changes and run the debugger a few times, and was able to focus on the problem.

Song.h:
Code:
#ifndef SONG_H_
#define SONG_H_
#include<iostream>
#include<string>

[Code] ....

I ran a step by step debugger, and found out the problem lays with line 90 in RadioManager.cpp, when the while loop runs its fourth iteration. It crashes when it tries to dereference the iterator, while it points to the fourth playlist in the list.

And here's some more weird stuff: when I comment out line 73 in main.cpp - it works perfectly fine! (line 73 in particular! commenting out any other line in main.cpp didn't worked around the bug!)