My screen has a dead “click” zone

The weirdest thing is happening to me – there is a dead zone on my screen where I can’t left-click up on the right side of the Screen. On SO, it covers parts of the toolbar. I can click the left two-thirds of my profile link, but not the right 1/3, and I can’t click on the inbox icon, trophy icon, help icon, or stack icon. I also can’t click on the right side of the higher hot meta posts. I also can’t even close this window normally – the minimize, maximize, and close buttons won’t work. If I have an internet tab over to the right, I can’t close it.

However, I can RIGHT-CLICK in the dead area, and when I do, it says “CTRL+C,” but greyed out.

Is there an invisible window up or something?