I just received the starter kit a few days ago. Everything was working perfectly until about 15 minutes ago.
After building the DC motor circuit exactly how it is shown in the example, I hooked up a 9-volt battery to the board, and the motor didn't turn. So I plugged in a 12-volt DC adapter, and the motor worked a little too well. It frightened me a little; I unplugged the power source.
Now, no matter what I connect the board to, USB or otherwise, the TX and RX lights remain on constantly, and the reset button doesn't work at all. The board is unrecognized by Windows, and it won't allow me to re-install the driver.
The Arduino IDE only says that the board on COM4 is not available, and no further information could be gathered even with verbose output during both compilation and uploading.