Window Auto-Drop Problem

I'm having some trouble with the auto-drop feature on my 2005 GT. A while back we got some rain here in SoCal, and it caused the auto-drop on the passenger side to freak out. When I would open the door, after about 20 seconds, it would go up, then down, then up, then down, and eventually end up (with the door still open). Well, it doesn't rain all that much here, and the problem went away. So a couple of weeks ago we had some rain and it started doing it again.
It sounds like the problem is the door switch. On old cars the switch was in the door jam, but on my Mustang I don't see one. So it that switch in the door? Or could the problem be something else? When I first got the car I had the leak under the dash on the passenger side fixed, but could there still be a leak that is getting to the wires? I don't know. It's probably just the switch.
Any help would be appreciated!
Rick

Actually, I don't think I was clear... I think I mis-stated when I called it the auto-drop... The problem isn't the feature that lets you roll the window down with a touch of the button. It's the little 1/2" drop that happens when you open the door.
The window works fine with the switch, and it will go up and down with one touch of the button. I don't have the global thing that lets me put the windows down with the key-fob.
So when it rains, the window goes up and down, but only that little 1/2" amount...

I already tried the window switch trick to relearn the limits, and that didn't help. Back in 2006 I noticed the passenger floor was wet after a rain so I took it in. They fixed that leak, and the floor hasn't gotten wet since... I don't know where the leak was, but it should be fixed. Where exactly did that leak come from? Was it at the firewall or somewhere else? (like the black trim above the passenger window)
Rick