Recently, I think since the update to 10.6.3, i've been having weird display issues. Sometimes I have black boxes around windows, icons in the finder aren't highlighted when selected, all of my icons turn white in the application switcher, icons are missing from the menu bar, little black or white boxes show up in the dock, black horizontal lines cling to the outside of the iTunes window, or the windows have no shadow. It is usually fixed after restarting the Finder, but comes back later. Any ideas about what is causing this or how to fix it? Thanks.