Desktop icon's drop shadows cannot be shown always

Hi,

Under SP2, my desktop icons are transparent and under computer ->

advanced -> performance -> settings -> visual effects everything is

selected and ''use drop shadows for icon labels'' is selected but

still after some refresh i get drop shadows displayed, after i open

some windows or applications or if i select them, this option

(shadows) has no effect. They're not shown.

But if i refresh desktop numerous times sometimes i get them back, but

if i select an icon or select an rectangle area or open some window,

they're immediately removed.

My settings: "Lock desktop items" is disabled, active desktop is

totally disabled.

I've updated my display driver to the latest.

How to fix it?

Thanks.