Arduino Uno Problem Uploading

I cannot upload programs to my Arduino Uno Board. When I try, I get the following message:

avrdude: stk500_getsync(): not in sync: resp=0x00
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51

I have restarted my computer, uninstalled and reinstalled the software, and updated the drivers.

Any suggestions?

What operating system? Do you have anything plugged into the Uno apart from the USB cable?

I just solved the issue. Whenever a pin is plugged into the Rx spot, it will not upload, but when unplugged it works just fine.