James C4S: That's what I needed! How do we get that information added to the Troubleshooting document for uploading?
beergnome: I do indeed have an Ethernet shield for this project... but I couldn't even get the code onto the Arduino, so it wasn't that.
So you disconnected the shield from the Arduino and it still doesn't program? You tried that?
Add: I had to find this post. Here is the post of another user. He is using a Mega, but they use the same usb/serial pins as the Uno.
I did just notice that the ebay auction for the ethernet shield says:
(Buyer please note that you may have to upload sketches to the Arduino mainboard without attaching this ethernet shield on it. Otherwise the sketches could not be uploaded.)
... I didn't notice that before... I haven't tried to upload something - then reboot with the shield attached....
Add2: If my evaluation of the problem is correct, you will also have problems with any Serial functions with the shield connected, but they will work fine without the shield.
If this is the case, and you are a gambling man, which I am
, you might try "pin bending" digital pins 0 and 1 on the shield so they do not insert into the Uno header when the shield is connected.