Whenever I open the iTunes store, the home pages of all of the sections (Music, App Store, Films etc) are black. They still have clickable hyperlinks, but I can't see what I'm clicking. Any pages accessed through the drop-down menus or by randomly clicking are fine. I also get similar results when I attempt to open iTunes Help. I'm using iTunes 10.1.1.4 on a Windows 7 PC. Any ideas?