If you are using LR3 (not sure about older versions) have you checked your Profile, under the Camera Calibration menu in the Develop Module ? Try changing it to the other options available to see if this gives you something similar to what you see on the screen on the back of your camera.
|Path to infinity by Kaye Cee Alolod|
from Your City - Streets with Vanishing Point
|Red Barn by PinoC|
|Gold Light by ecastellon|
from My Best Photo of the Week