Also a new user and I had the very same issue yesterday on my Win7 machine. Tried a number of things I found here and searching the web in general, different USB cable, pressing reset button, tried a Vista machine instead of the Win7, back to Win 7 machine but the Micro would not show up in Device Manager.
Worked with it for aver an hour and finally double and triple clicking the reset button it would recognize the USB device as an Arduino Micro but it failed to load the driver and disappeared from Device Manager again. After a couple more tries it successfully loaded the driver. Unfortunately not sure what the magic combination was to get it to work. I did hold reset button down while plugging in USB cable on the laptop and then double clicking it, maybe that was the solution...not sure.
Now it finds it every time it the USB is plugged in no matter which cable I use. Happy it is working, wish I knew exactly why to help others.