Sketch won't upload with shield on the arduino

Hi,

I have this problem on the Arduino Uno.
I was uploading a sketch to the arduino, with the shield on it, and it wouldn’t finish. It had the progress bar right before the end, but it wouldn’t finish. So I had to disconnect the USB cable from the arduino, and reconnect.
Now when I try to upload the sketch again I get this :

Binary sketch size: 7,006 bytes (of a 32,256 byte maximum)
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x00
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0x00
avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0x00
avrdude: stk500_getsync() attempt 4 of 10: not in sync: resp=0x00
avrdude: stk500_getsync() attempt 5 of 10: not in sync: resp=0x00
avrdude: stk500_getsync() attempt 6 of 10: not in sync: resp=0x00
avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0x00
avrdude: stk500_getsync() attempt 8 of 10: not in sync: resp=0x00
avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0x00
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0x00

If I remove the shield, it uploads. And then I put the shield back and it works.
How do I go around this ? Its annoying having to remove the shield every time I want to upload.

Thanks,
Regards

Hi,
I had a connection made on PIN 0. It is part of the circuit. I am doing serial communications with the RX/TX pins. To upload I have to disconnect it first. and the reconnect.

Regards