After talking on the phone for a while, I experienced the problem discussed in the thread below, where the touch screen started acting erratic clicking buttons that I never pushed, and I had to pull the battery to turn the phone off.
When I started the phone, I noticed that the home screen was messed up:
1) All of the icons are missing their labels.
2) The menubar containing the dialer and contacts button is now vertical instead of horizontal.
3) All of the icons on the applications menu are smooshed together.
I tried every gesture and button I can think of. How can I fix this?