Lately a section of my phone's* screen has become unresponsive to touch. Attempts to tap this untappable section result in a tap registering randomly around the problem area.
I can't draw in the area in Draw Something, and in Angry Birds, I can only aim my birds down as moving my finger down into the untouchable area results in the bird launching and the direction not changing. Attempting to type with the phone on its side renders the letters around A,S,D,Q,W, and E unusable (virtual keyboard). It is also impossible to select the "Users" tab on the mobile version of any SE site.
What causes this? Can I fix it? If so, how? How can I prevent it from happening to my next phone?