What to do if your computer freezes:
1. Don't panic. Gently unplug the computer.
2. Move the computer to a warm location, but not too hot. Near a heater or fireplace (not too near!) is good.
3. Place a towel under it to collect run-off.
4. Do not use any sharp objects to remove ice, especially on the motherboard. Remove any large pieces of ice that fall off.
5. When the computer is unfrozen and completely dry, plug it back in and test it.