Dell M4800 Touchpad keeps turning itself back on

Having a strange issue with the Touchpad on my Dell Precision M4800. When I disable it using the Dell software or using the Fn+F5 hotkey, it has a tendency to come back on after a random interval of time. I want it to stay turned off permanently, as I prefer to use the Pointstick exclusively.

When using the Fn hotkey, I get a notification onscreen as well as a popup in the system tray saying "Touchpad notification: Your touchpad has been disabled." If I manually disable it through the Dell Pointing Devices software, I get the same effect, but without the notification. In either case, this works great... for awhile.

But then the Touchpad inevitably turns back on. I often don't notice until suddenly my mouse cursor is behaving erratically, at which point I try to swipe my finger on the touchpad and sure enough, it's become enabled again.

However after some further experimenting it turns out the "random" aspect of this is not totally random and I can reproduce the issue quite reliably by furiously scanning my finger back and forth across the Touchpad for a few seconds. Inevitably, the touchpad will turn back on, and I will get the notification "Your touchpad has been enabled." No buttons or hotkeys are pressed, all I have to do is move my finger on the touchpad surface rapidly and within seconds of starting to do that, it will re-enable itself. Again, there is also a notification that it has been re-enabled when this happens, so the software is detecting my finger movements somehow, perhaps I am accidentally performing some "magic gesture" that compels it to re-enable the touchpad.

If I don't intentionally try to cause this, it still turns on eventually, but can take a long time, half an hour or more before it becomes enabled again. I assume it's the activity of my palms resting on it that will accidentally turn it on again in the same way as swiping my finger intentionally across the disabled touchpad. It makes no difference whether the Dell Pointing Device software is open or closed and this will happen when any application is open.

All I want is for the touchpad to be truly disabled permanently and not accidentally turn on in the middle of my work. But at the same time I'd prefer to leave the pointing stick enabled, so I can't simply remove the driver. So far I've been using an external mouse and disabling all internal pointing devices, which works ok, but like I said I am fond of the pointing stick, I'd prefer to be able to leave it on with JUST the touchpad disabled.

System specs: Dell Precision M4800 with qHD screen

CPU: Core i7 4800MQ @ 2.70Ghz

Graphics: nVidia Quadro K2100M

OS: Factory-installed Windows 7 Pro 64-bit

Dell Pointing Devices software version v.8.1200.101.134