Screen registers multiple phantom touches
First, make sure your screen is clean and there is no debris hidden at the top.
Second, the screen may need to be (re)calibrated. You also might try clearing existing calibration data and recalibrating the screen.
On this page there is a "To adjust calibration" section that tells you what options to go to. This is for Windows 7, I'm betting it hasn't changed for Windows 8 (I could be wrong):
Open Tablet PC Settings by tapping the Start button , and then tapping Control Panel. In the search box, type Tablet PC Settings, and then, in the list of results, tap Tablet PC Settings.
On the Display tab, under Display Options, tap Calibrate. If you're prompted for an administrator password or confirmation, type the password or provide confirmation.
Follow the instructions on the screen, and then tap Yes to save your calibration settings.
Notes • To perform a 16-point calibration again, in the Tablet PC Properties window, tap the Reset button. If you're prompted for an administrator password or confirmation, type the password or provide confirmation. Tap OK, and then tap the Calibrate button.
• If you begin a 16-point calibration and your screen is set to Portrait orientation, it will change temporarily to Landscape during the calibration.
Try doing the "16-point calibration" it talks about.
If the screen behaves erratically after that, I'd say it's defective and needs to be serviced and/or replaced.