Icons disappeared after FC3->FC4 upgrade
 

I just upgraded from FC3 to FC4 and the first thing I noticed is that several of the icons on my desktop are gone. Items like 'Computer' and 'Trash' now have just a blank page as their icon. (Also the "hide all windows" button at the lower left has no icon; I'm not sure if that's related or not.)

Is there anyone else who's experienced this, or who has a suggestion? Thanks.