Hello philly_cat,
This is Kevin from Palm Inc. Are you using an adhesive screen protector? If it is trapped under the screen edge, it can interfere with touchscreen calibration. Occasionally, just having the screen protector on the screen can cause the issue. Try removing it to see if that makes a difference.
Or, there might be debris trapped under the edge of the screen. Use the corner of a piece of thin, stiff paper (copier paper works well) to very gently slide all around the edge of the screen. Don't let the corner of the paper travel more than an eighth of an inch under the screen edge frame. By doing this, you may be able to dislodge small particles of debris trapped under the frame.
You might take a look at the Palm Knowledge Library article
"Calibrating your touchscreen (digitizer)", as it has
a couple of other troubleshooting steps, as well.
Sincerely
Kevin