avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51 Error on Arduino IDE

If you are receiving the following error from Arduino :

avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51

Double check if you have the right Arduino board selected. The most common cause of this error (IMO) used to be people choosing the Duemilanove 128 when they had the newer Duemilanove 328.  Click on Tools - Board and make sure you have the right board chosen, and try again.