Probably you lost your drop shadows under icon labels. It's in System
properties (right click on My Computer and select Properties, then go to the
Advanced tab, then click Performance and look in the box at the bottom.
Second item from the bottom. You need to select Custom I think).
You need *four* things to have transparent icons:
1) Hold down the Windows key and press Pause/Break. On the "Advanced"
tab, under "Performance" click "Settings." On the "Visual Effects"
tab, make sure the box "Use drop shadows for icon labels" is checked.
2) Right-click on the Desktop, and make sure that "Arrange Icons by"
"Lock Web items" is not checked.
3) Right-click on the Desktop, and choose Properties. On the "Desktop"
tab, click "Customize Desktop," then on the "Web" tab, uncheck all
boxes.
4) Make sure any Wallpaper is an image file. Html will stop the
transparency.