Windows go down on their own.
 

Sometimes my windows, both driver and passenger side, would go down without any action from me. I can put them up with buttons tough. It's not like loose mechanics or broken cable: the glass seems to be solid in place, no movement if pulled by hand. It's like some phantom signal from a shortened switch cable. Strange thing about it is that both windows would go down completely in a synchronous manner. If it's a faulty switch I would guess only one window would do it.

Do they drop all the way down, or only a few inches?
If they both drop a few inches, you have a faulty top latch micro switch.

Not a few inches. Sometimes it's a half. Sometimes it completely goes down.

I'd suspect the top latch too but with them dropping all the way it has me thinking it might be something else. I had a friend's car that was doing that. I replaced the latch and wiring harness connections before I found out that the problem was with the fuse/relay box. A mouse had built a nest behind it and in the process pulled some of the wires out just enough to cause inconsistent problems like yours.

Maybe mine is weird but my windows would also occasionally drop all the way down. The only way to get them back up after they dropped on their own would be to press the microswitch in by hand while holding the window up button.

I had windows do weird crap a few years back that was solved with new ignition switch. Can't remember what they were doing but it more than the little drop associated with top microswitches.

Definitely start with checking for moisture under the drivers seat and replacing the ignition switch. ;)

Eventually it was the ignition switch. But I replaced the top switch too. Luckily I did not waste $60. I just replaced Cherry sub-micro with Omron D2HW-A201D
http://www.mouser.com/ProductDetail/Omron-Electronics/D2HW-A201D/?qs=SXIVkn%252bm38luavE3Ud%2FnHw%3D%3D