I just received from Newark (Element14) my first UNO Rev3 unit. I cannot get my computer to sense or recognize it, meaning it doesn't show up in device manager anywhere after powering up, nor as an 'installing device' message balloon. Actually, I have tried 2 WIN7 and 1 XP machines, and 2 different USB cables (both of which worked on printers). None of the machines sensed the UNO when I plugged in the USB cable. Since Windows didn't sense them, I tried to force installation of the device driver on a WIN7 64bit machine, but after doing so Windows reported a Code 10 error, and that the device was not working. (I had previously downloaded the arduino-1.0.3-windows software and used the driver folder as the target for the driver.)
The UNO unit shows a lit green power LED, and the pin13 LED blinks rapidly and sporatically for about 5 seconds and then settles in to an ON/OFF period of about 1 second (half on, half off).
Any thoughts? Thank you for your help.