It sounds to me like a regulator problem...
it's operating in the same way as if you've got your arm stuck, the regulator can tell this and automatically opens the window, it works on pressure applied to the regulator (strain),
maybe the window needs realigning.. with the door card off loosen the two nuts that holds the window in place now try and get the window shut all but 3inches from the top, there should be two holes just right for a socket and ratchet to fit on the inside of the door, then tighten up the two nuts.
or you could try and detach the window and unbolt the mechanism from the door and try operating it just out side the door as you will need the power cable attached
give it a go if not its a new regulator but you might as well get the whole mechanism from here in Parts for sale or off ebay