Arduino UNO SMD Edition - avrdude: stk500_getsync(): not in sync: resp=0x30

Development Tools IDE 1.x
1

Hello,
I've been using my brand new arduino uno smd edition for 3 days.
Today i tried to upload a sketch but it gives me an error: "avrdude: stk500_getsync(): not in sync: resp=0x30".
It didn't give me problems until today! it worked perfectly.

I'm using a Macbook (Mountain Lion).
that's what i've tried to do:
-change cable
-try on another mac (same error)

I've been using another arduino uno for one year, it still works well and it never gave me problems.
I say this because this other arduino works well on the same computer, as i can upload sketches without problems.

How can I try to fix this problem?
Thanks

2

What was the also sketch that you uploaded and what hardware have you connected to it before? (Not just what was connected when the problem started)

3

Thanks for the reply.
I connected it only to my Macbook (Mountain Lion).

That's the sketch that I uploaded.
It worked well, and then it stopped working.

that's the code:

void setup(){
  
 pinMode(A4,INPUT);
Serial.begin(9600); 
}


void loop(){
  
Serial.println("");
Serial.println("");
Serial.println("");
Serial.println("");
Serial.println("");
Serial.println(analogRead(A4));
delay(100);
}
4

are you using arduino IDE 1.00 or above?

5

Arduino 1.0.3

I'm currently using my other Arduino uno and it works perfectly on the same Macbook. I can upload sketches without problems.

Could you please help me? what should I do?
I really want to solve this problem, because i paid 24€ for something that doesn't work.
I contacted the shop, and they told me that it's not their problem. They also told me I should contact Arduino and pay all the shipping costs involved in order to fix my problem.