whu??
I think what it is is that well known hide inactive icons option
there are two seperate items - both of which need attention.
right click the desktop | properties | desktop | customise desktop
take the tick out of run desktop ckeanup
then
right klick on the taskbar
properties | taskbar
take the tick out of hide inactive icons.
http://search.live.com/images/results.aspx?q=h ide+inactive+icons&mkt=en-gb
why oh why oh why MS thought these were a good idea I have no idea.
I'm having a bit of a grey moment - I'm damned if i can remember how to restore the ones that have gone ....