Can you attach a screenshot?

• http://en.wikipedia.org/wiki/Screenshot

Use a compressed image type like PNG or JPG to save the screenshot and make sure that you do not exceed the maximum file size (1 MB).

Make sure that you allow pages to choose their colors and that you haven't enabled High Contrast in the Accessibility settings.

• Tools > Options > Content : Fonts & Colors > Colors : [X] "Allow pages to choose their own colors, instead of my selections above"

• http://kb.mozillazine.org/Website_colors_are_wrong
• http://kb.mozillazine.org/Websites_look_wrong

• http://www.microsoft.com/enable/products/windows7/default.aspx
• http://windows.microsoft.com/en-US/windows7/Make-the-computer-easier-to-see-optimize-visual-display

There is also an option to disable loading of images. Maybe you have enabled it by accident? To see if it is activated go to the options window, select the content tab and it should be the second checkbox labeled "load images automatically". If it is disabled, re-enable it. If it is already enabled click the exceptions button next to it and see if there are rules there that could explain the behavior.