I have a 2004 Gateway 5200x computer. I can no longer change the background except for the color, the lists of background is frozen.

Which operating system ??
Is it for computer background or a program ??..
Make a Black Background White

The desktop appearance of a computer equipped with Microsoft Windows XP, whether PC or laptop, can be customized easily.
Users can change background color, background image, frame color, font size and the arrangement of desktop icons.
Five easy steps how to change the desktop background color from black to white.
Changing Background Color
Right-click the mouse on any open portion (i.e., non-icon) of the desktop, which will open a menu. Select "Properties" at the menu's bottom, which will open the "Display Properties" application.
Click the "Desktop" tab at the application's top.

Click the down arrow next to the "Color" button, and select the white color.


Click the "Apply" button, then click "OK" to close the application.


http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/display_change_background_color.mspx?mfr=true

I assume you are talking about the desktop background that appears with your icons after the system boots up.
Go into the Control Panel and change the Desktop Background.

Click Start/Control Panel and look for Display or Personalization and Appearance and change the background on the display.

Windows 7 Starter edition comes with one desktop background, which can't be changed or customized. Please see this link for details.

http://windows.microsoft.com/en-US/windows7/Personalize-your-computer

To change the desktop background

1. Open Desktop Background by clicking the Start button , clicking Control Panel, clicking Appearance and Personalization, clicking Personalization, and then clicking Desktop Background.
   

2. Click the picture or color you want for your desktop background.
   

   If the picture you want to use is not in the list of desktop background pictures, click the Picture location down arrow to view other categories, or click Browse to search for the picture on your computer. When you find the picture you want, double-click it. It will become your desktop background and appear in the list of desktop backgrounds.
   Look for pictures in other locations on your computer

3. Under How should the picture be positioned, choose to have the picture fit the screen, tile, or be centered on the screen, and then click OK.
   

Note

If you choose to have a centered picture as your desktop background, you can also have a color background to frame your picture. Under How should the picture be positioned, click Change background color, click a color, and then click OK.

To change the desktop background

1. Open Desktop Background by clicking the Start button and clicking Control Panel. In the search box, type desktop background, and then click Change desktop background.
   

2. Click the picture or color that you want to use for your desktop background.
   

   If the picture you want to use isn't in the list of desktop background pictures, click an item in the Picture location list to see other categories, or click Browse to search for the picture on your computer. When you find the picture that you want, double-click it. It will become your desktop background.
   Look for pictures in other locations on your computer

3. Under Picture position, click the arrow and choose whether to crop the picture to fill the screen, fit the picture to the screen, stretch the picture to fit the screen, tile the picture, or center the picture on the screen, and then click Save changes.
   

Note

If you choose to have a fitted or centered picture as your desktop background, you can also frame your picture with a color background. Under Picture position, click Fit or Center. Click Change background color, click a color, and then click OK.
Tip

To make any picture stored on your computer (or a picture you are currently viewing) your desktop background, right-click the picture, and then click Set as Desktop Background.
The Set as Desktop Background option

You can add more desktop backgrounds to your collection from the Personalization Gallery on the Windows website.

This can be found in the Help and Support section of Windows on your laptop.

To change the desktop background

1. Right click on your desktop-Select personalize. This will open a window that asks you to select your desktop background
   
   

2. Click the picture or color that you want to use for your desktop background.
   

   If the picture you want to use isn't in the list of desktop background pictures, click an item in the Picture location list to see other categories, or click Browse to search for the picture on your computer. When you find the picture that you want, double-click it. It will become your desktop background.
   

   Look for pictures in other locations on your computer
   

3. Under Picture position, click the arrow and choose whether to crop the picture to fill the screen, fit the picture to the screen, stretch the picture to fit the screen, tile the picture, or center the picture on the screen, and then click Save changes.
   

Note

• If you choose to have a fitted or centered picture as your desktop background, you can also frame your picture with a color background. Under Picture position, click Fit or Center. Click Change background color, click a color, and then click OK.
  

Tip

• To make any picture stored on your computer (or a picture you are currently viewing) your desktop background, right-click the picture, and then click Set as Desktop Background.
  

The Set as Desktop Background option

Too many varibles ,but I'll give it a try. are there any layers? does the background layer ( the one called background at the bottom of the list in the LAyers palettte) have anything in it? area all the visible layers above the "background" transparent where they are "white"? If this is the case it's much easier than if any of the layers are "white" or some other color- then you need to select out the items you want not to change color, using any number of the available "selection" tools, from the area you want to change color- now that can be a challenge.

If it has an onboard video card then reload the video driver.

If it has a PCI-e / AGP video card then download latest drivers and re-install driver, Dont forget to un-install original driver first.

Failing all that see if you can edit the screen resolution in safe mode. (Press F8 when you first switch PC on.

http://support.gateway.com/support/drivers/getFile.asp?id=20260&dscr=Realtek%20High%20Definition%20Audio%20Driver%20Version:%205.10.0.5136&uid=233511939
download from here.

Early 2005.