I get this when I try to upload an example sketch. What is it? Working with windows Xp.
It means something went wrong in the communications with the Arduino board:
Driver not installed.
Wrong Serial Port selected under Tools->Serial Port
Wrong Board selected under Tools->Board
Bad USB cable.
Wrong bootloader in the ATmega chip.
Previous Arduino sketch is flooding USB cable with output.
USB-to-Serial device isn't working (on UNO or MEGA the 8U2/16U2 may need re-flashing)
There is hardware connected to Pin 0 or Pin 1 that interferes with the serial signals.
Did everything work before?
What do the RX and TX lights do when you try an upload?
For awhile everything worked great. When I started working with motors, this started happening. In order for me to make it work, I had to reinstall the driver to use it.