1) Is the Screen resolution set correctly?
Native screen resolution should be set to 1024 x 600.
Right-click on an empty area of your desktop screen.
Go to the bottom of the list, and click on - Properties
The Display Properties window will come up.
Click on the Settings tab.
Down in the middle of the Display Properties window, you will see Screen resolution in blue.
There is a Slider. In WinXP it is an Arrow, with a Green tip on top, and bottom.
Left-click on the Slider, hold the left mouse button down.
Now move your mouse to the Left, to drag the Slider to Less screen Resolution, or to the Right to Increase.
Stop at 1024 x 600 pixels.
Also the Color quality should be set to Highest (32 bit)
Click on the blue down arrow to the right of the Color quality box.
In the list click on Highest (32 bit)
Go below to the Right, and click on Apply.
Now go below to the Left, and click on OK.
If that doesn't cure the problem, the problem is a hardware issue.
Problem will be;
1) Graphics chipset,
2) Video Cable,
3) LCD screen
[The Backlight used is LED backlighting. Uses a series of LED's.
Light Emitting Diode.
There is NO screen Inverter ]http://www.dell.com/support/Manuals/us/en/19/Product/inspiron-mini9
If it is a hardware issue, I can guide you through the diagnostic flowchart, to see what the problem is, and step by step.
Post back in a Comment.