OK, I tested this using MaplePaint on my PE and EE, at night, about 2 feet from a lamp (and right under the lamp -- didn't seem to make a difference). Used both the Edge stylus and Motion L-series pen.

It was much easier to get the PE to misbehave. At first, I could only get spikes by resting the edge of my writing hand on the screen or making contact with the optical mouse. Then I went and rubbed my feet on the dogs' futon (no rugs, so that's my best source of static), and that seemed to make a major difference. I was using the Motion pen on a metal split ring and I held my hand way up so that no part of it was remotely near the screen -- only the pen tip was in contact, and I was getting spikes shooting up to the left away from where my hand was. This was only on the PE. The angle of the light source may have entered into it as well.

The only thing that gets the EE to react is direct physical contact of my hand with the screen.

So either your PE is calibrating itself extra sensitively, or you are very static-y or metallic at present, is my unscientific guess. Maybe recalibrate the LCD screen one more time, and when you touch the targets, really wham them a bit forcefully so it thinks you have a heavy touch? I wonder if that would help any.