On the new Microsoft Windows Vista or on Windows XP, it automatically ads a shadow to the text under the icons on the desktop.  On some backgrounds, this can help to make the text more readible.  However, on others it can have just the opposite effect.

To enable or disable this feature go to the System Properites window (a shortcut to that window is to hold down the Windows key - the one with the flag) and hit the Pause/break key).  In XP click the Advanced tab and on Vista click on the left side of the window over the "Advanced system settings" option.

Click the "settings" option and under visual effects.  Then set or clear the check mark on "use drop shadowns for icon lables on the desktop" and click OK.