iTunes on Windows 7 ceased expanding miniplayer after Ctrl click on thumbnail artwork.

During playback, iTunes used to expand the miniplayer album art, to full screen size, when holding the Ctrl key and clicking on the thumbnail at the top of the screen. Now the same Ctrl + click has no effect. However, after doing it, I get a double icon in the task bar, one for the complete iTunes and another for the full size mini player, except that the full size mini player cannot be found anywhere, only that icon in the task bar. And sure enough, I can click on the x at the corner of this "ghost" icon, and the icon will close, but the explandable album art never shows up. The whole thing is as if iTunes still thinks that it's working just fine, but it's not. This looks like a corrupted registry key would cause it. I tried uninstalling iTunes, rebooting the computer, and reinstalling, but this didn't help. Is this a known issue? Any ideas how to fix it? Thanks for any support.