So far the only trick that works is to turn off the touch keyboard and handwriting service:
- Go to Control Panel > Administrative Tools > Services.
- Stop the Touchscreen and Handwriting service.
- Set it to disable so it don't come back.
Update 2: Turns out that turning off this service also disables the Tablet PC Settings control. I discovered this when I wanted to try calibrating my screen again, since I am using both my 2-point optical touchscreens in a slightly-reduced resolution so I can get the slide-in-from-the-edges features of Windows 7.
Update 1: Note: At first I tried to turn off using the following method but it didn't work for me.
- Right-click an empty area of the taskbar.
- Click the Toolbars tab.
- Clear the touch keyboard check box.
- Click OK.