user26399: I've been playing with my Arduino Boards for a while. I have an Arduino Nano and a Duemilanove 328.
I've been able to program both of them without problems for weeks. Any example project I try will compile and upload with no issue.
I recently got an Ethernet shield... I'm trying some test sketches and no matter which board I try, with the shield attached I get:
avrdude: stk500_getsync(): not in sync: resp=0x00

As I said, without the Ethernet shield attached all is bliss....
Do I have a bad shield or am I just doing something stupid?

user23674: The Ethernet Shield uses the pins  D10, D11, D12 and D13 on the Arduino UNO. I presume there is a conflict and you use one or more of these digital pins in your setup already.
A nice overview of possible conflicts between shields and arduino boards can be found at: 
http://playground.arduino.cc/Main/ShieldPinUsage 

26399: <p>I've been playing with my <a href="https://www.sabdel.com/shop/electronics/5v-4-channel-relay-shield-expansion-board-for-arduino/" rel="nofollow noreferrer">Arduino Boards</a> for a while. I have an <a href="https://www.sabdel.com/shop/electronics/328p-multifunction-expansion-board-v3-0-for-arduino-nano-uno/" rel="nofollow noreferrer">Arduino Nano</a> and a Duemilanove 328.</p>

<p>I've been able to program both of them without problems for weeks. Any example project I try will compile and upload with no issue.</p>

<p>I recently got an Ethernet shield... I'm trying some test sketches and no matter which board I try, with the shield attached I get:</p>

<pre><code>avrdude: stk500_getsync(): not in sync: resp=0x00
</code></pre>

<p>As I said, without the Ethernet shield attached all is bliss....</p>

<p>Do I have a bad shield or am I just doing something stupid?</p>
 23674: <p>The Ethernet Shield uses the pins  D10, D11, D12 and D13 on the Arduino UNO. I presume there is a conflict and you use one or more of these digital pins in your setup already.</p>

<p>A nice overview of possible conflicts between shields and arduino boards can be found at: 
<a href="http://playground.arduino.cc/Main/ShieldPinUsage" rel="nofollow">http://playground.arduino.cc/Main/ShieldPinUsage</a> </p>
