I recently purchased an Arduino Leonardo to control my Sumo robot. I plugged it in to my friends computer and was able to use the Arduino IDE to upload code to the board and run a simple wheel-test program. When I got home and sat down to play around with it myself, I discovered that it wouldn't connect to my computer.
I plugged the micro-usb in to my computer and the board turns on and the LED goes into it's two-second pulse, but Windows 7 64bit never auto-detects new hardware. I've searched around on Google and tried some of the things that were suggested and it still doesn't work.
I manually installed the Leonardo driver in the System section of the Widows Control Panel and it still doesn't register the device. I've tried manually changing the port of the device from COM1 all the way up through COM9, hoping that my computer was just stupid and didn't recognize what it was doing.
I'm using a Gateway laptop (I looked around for a model name or number, but it doesn't seem to have one. It's just a cheap development machine that I bought at Wal-Mart)
Solution: The crappy USB cable I was using did not have a data connection, so even though it would power the board, Windows was never able to establish a connection to the device. Terrible cable. :(