YUN issue using fswebcam command from a ino sketch to upload pict to DropBox

I am checking the fswebcam Linux comand to send periodically a picture to Dropbox. All is running only during ok only during the first 5 cycles, the arduino take the picture and it is uploaded on the Dropbox folder.
Afterthat the White led of the YUN is OFF and the runshellcomands loo they are not running so far. And this is the result from the Arduino IDE console:

Setup Bridge stablished (following paragraph is translated by me and it repeats 5 cycles)
1..Sent command fswebcam to Linux
2..Returned code after taking runshell command fswebcam____0
3..Sent command to upload to Dropbox
4..Returned code by the runshellcommand to upload to Dropbox____0
Cycles: 1

1..Enviado comando fswebcam a Linux
2..Código devuelto al hacer foto____0
3..Pedido subir foto a Dropbox
4..Código devuelto al llamar a Dropbox____0
Ciclos: 2
1..Enviado comando fswebcam a Linux
2..Código devuelto al hacer foto____0
3..Pedido subir foto a Dropbox
4..Código devuelto al llamar a Dropbox____0
Ciclos: 3
1..Enviado comando fswebcam a Linux
2..Código devuelto al hacer foto____0
3..Pedido subir foto a Dropbox
4..Código devuelto al llamar a Dropbox____0
Ciclos: 4
1..Enviado comando fswebcam a Linux
2..Código devuelto al hacer foto____0
3..Pedido subir foto a Dropbox
4..Código devuelto al llamar a Dropbox____0
Ciclos: 5
1..Enviado comando fswebcam a Linux
2..Código devuelto al hacer foto____1803
3..Pedido subir foto a Dropbox
4..Código devuelto al llamar a Dropbox____1803
Ciclos: 6

I have tested the fswebcam command directly from the PuTTY console, and it Works well if I enter
fswebcam picture.png, been at /mnt/sda1

But , if I repeat same command with less tan 10" in between, the linino looks carshes, the White led is off and it goes ON again after a minute. For this reason I put 15 seconds in the sketch.

Attached the code: ( When the issue appears, I need to disconnect the USB plug to remove the 5V to the YUN.


// Sketch to upload pictures to Dropbox when motion is detected
#include <Bridge.h>
#include <Process.h>

// Picture process
Process ProcesoLinino1,ProcesoLinino2;

// Filename
String filename;
String a;

// Pines
const int hacerfoto = 8;
const int pin12 =12;
const int pin13 =13;
int n;

// Path
String path = "/mnt/sda1/"; //Ruta donde está la tarjeta SD en el YUN
boolean success_foto = false; // a flag to indicate whether we've uploaded the file yet
boolean success_dropbox = false; // a flag to indicate whether we've uploaded the file yet
void setup() {
Bridge.begin();//Para poder lanzar funciones de la parte de Linino, hay que activar el Bridge. LED blanco ON
Serial.begin(9600);
while(!Serial);
Serial.println("Setup Bridge establecido");
// Set pin mode
pinMode(hacerfoto, INPUT);
pinMode(pin12, OUTPUT);
pinMode(pin13, OUTPUT);
n=0;
}

void loop(void)
{
if (!success_foto) {
success_foto=true;
digitalWrite(pin12,HIGH);
digitalWrite(pin13,LOW);
filename= "Pepito10.png";
Serial.println("1..Enviado comando fswebcam a Linux");
ProcesoLinino1.runShellCommand("fswebcam " + path + filename + " -r 352x288");
while(ProcesoLinino1.running());
Serial.print("2..Código devuelto al hacer foto____");
Serial.println(ProcesoLinino1.exitValue());
ProcesoLinino1.close();
success_dropbox=false;
}
delay(15000); // to avoid linino crash
if (!success_dropbox) // Upload to Dropbox
{
success_dropbox=true;
digitalWrite(pin13,HIGH);
digitalWrite(pin12,LOW);
Serial.println("3..Pedido subir foto a Dropbox");
ProcesoLinino2.runShellCommand("python " + path + "upload_picture.py " + path + filename); //I eddited the *.py file with my Temboo account data
while(ProcesoLinino2.running());
n=n+1;
Serial.print("4..Código devuelto al llamar a Dropbox____");
Serial.println(ProcesoLinino2.exitValue());
ProcesoLinino2.close();
Serial.print("Ciclos: "); Serial.println(n);
success_foto=false;
}
delay(30000); // To guarantee dropbox is not saturated

}