This could be a driver problem. With your iPad connected via USB, open device manager - if you are using Windows 7 upwards you should just be able to hit the Windows Key on your keyboard and type Device Manager then hit return.
I'm guessing you'll see an exclaimation mark ! through your iPad in Device Manager, if that's the case right click the device and select uninstall.
Disconnect your iPad. I presume you have the latest version of iTunes installed, if not now would be a good time to install it. Once done or if already installed I'd restart Windows and then reconnect your iPad and see if it installs the driver ok this time around.