Odd applications screen behavior

Last week, I started getting a copy of my applications screen from Finder that cannot be closed. It sits with the revolving thing-a-ma-bob (what IS that? Not the color wheel) but doesn't close. If I minimize, it doesn't get the Finder icon in the lower right corner the way the real one does. 2011 MBA, 10.7.4 that is up to date on patches.

I should add this is an Apple installed Lion, and I've only had this MBA about a week. Don't know if it matters, but just in case someone was thinking I may have done something when updating or upgrading, etc.