First thing to do is try it on external monitor and see if the condition still exists. If it does show the same line then theres a problem with the video circuit, LCD cable or other..
I recently lifted my IMB Thinkpad T40 off of its docking station (while it was turned on) and from then on, there is a half inch white vertical line from the top to the bottom of the screen. I was wondering if taking it off the docking station caused this? I don't know where to go and can't find any other similiar problems like this out there. Please help!