Dell Inspiron 1501 screen half black

Had the same problem. Fixed it though. Here's how:
You'll notice that the screen comes back to life if you press down on the very top of the green line. This is because a controller circuit board behind the LCD screen (at the top) is pressure fit flat-surface-to-flat surface to the contacts on the back of the LCD. Eventually, the sticky substance that holds this circuit board in place wears thin, collects dust, etc.. and the connection between the circuit board and the lcd contact is lost. The line appears where this break in contact has occured. 
So, the solution is to increase the pressure at that point to reestablish the connection. I wasn't able to remove the circuit board to clean beneath it as it seemed too likely to cause damage. Nor would I have had the right adhesive to connect it back, so I simply removed the LCD and put a bunch of tape at that point so that it would "push" with a little more pressure when screwed back into place. Worked great.
To remove the LCD, pull off the 6 feet around the screen. Remove the screws behind them. Carefully pry off bezel with a small flathead screwdriver working your way around it. Once removed there are simply 4 screws on the left and 4 more on the right of the LCD to remove. Pull out screen carefully and start stacking bits of tape on the spot where pressure seems to work best. Put it back in and see if you've made any difference. I did this with the computer on so I could verify my results. Just be careful not to short out any naked contacts.
If this doesn't work for you, at least you'll know you just need to replace the LCD, not the video card. Easily found on ebay.

You have a bad grapics card in the laptop or he connections to the screen on your laptop came loose.
It happens dells are famous for bad or corupt displays try to hook it up to an external monitor if ya can.
if image on monotor is good ya got a screen malfunctioning in the laptop . dells are famouss for heat problems with there laptops.

Mcaramb you deserve a big shinny medal mate, that worked a treat, i have a dell 6400, had it 4 years and first problem i have came across, but again spot on pal

Same issue. Dell Inspiron 1545. Right half of screen white with colored vertical streaks.
Followed advice:
1. Remove the LCD
- Pull off the 6 feet around the screen.
- Remove the screws behind them with 3mm jewel cross tip screw driver
- Carefully pry off bezel with a small flat tip screwdriver (used 3mm). Pressing gently toward the center of the screen helps unlock the plastic latches. Working your way around it. The bottom is trickey, so do it slowly. The bottom requires working the flat tip screwdriver slowly across the entire surface of the bezel.
- Once the bezel is removed there are simply 4 screws on the left and 4 more on the right of the LCD to remove. Pull out screen carefully.
- Original auther suggested "start stacking bits of tape on the spot where pressure seems to work best."
- I cut a 1/4th of a piece of 8-1/2 x 11 paper, folded it 4 times, and inserted it between the green PCB and the translucent plastic protection covering the entire PCB. I did this directly behind the location where the ribbon cable connectes into the PCB assembly. This applied enough pressure to keep whatever was loose connected.

I still get the screen distortion when I hold the screen in certain spots. May add more spring to the PCB in the future, or purchase a new working LCD assembley from EBay.

Total job was < 30 minutes.