please help a beginner

Hey people... I'm new in C programing, and i'm having some problem.
What's wrong with the code below. I got no error compiling the file,
but when executing i get a *** glibc detected *** ./test: double free
or corruption (out): 0xbfe83468 *** error:

It's a simple code:

//file config.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "config.h"

int read_server_list(char *config_file, char **servers)
{
    FILE *file;

    int i, status;
    file = fopen(config_file, "r+");

    if(file != NULL)

    {
        printf("File opened.\n");
        status = SUCCESS;

        servers = (char **) malloc(MAX_SERVERS * sizeof(char *));

        if(servers == NULL)

        {
            printf("Memory out.\n");
            status = OUT_OF_MEM;
        }

        else
        {
            for(i = 0; i < MAX_SERVERS; i++)
            {
                servers[i] = (char *) malloc(MAX_CHAR_LINE);
                fgets(servers[i], MAX_CHAR_LINE, file);
                printf("%s",servers[i]); //prints OK
            }
        }

        fclose(file);
    }
    else
    {
        printf("Error openig the file.\n");
        status = FILE_ERROR;
    }

    return status;
}

void cleanup_server_list(char **servers)
{
    int i = 0;
    do {
        free( servers[i] );
        servers[i++] = NULL;
    } while( i < MAX_SERVERS );

    free( servers );
    servers = NULL;
}

and then

//file main.c

#include <stdio.h>
#include "config.h"

int main()
{

    int status;
    char *file = "text.txt";
    char **servers;
    status = read_server_list(file, servers);

    cleanup_server_list(servers); // HERE I GET THE ERROR

    return 0;
}