In Lion, it often happens to me that Cmd + W won't close a window, and Cmd + Q won't quit. I then realize that I'm unable to type anything anywhere, but I'm still able to switch desktops with Alt + Arrow Keys. If I open the keyboard viewer, every key I press on the real keyboard becomes highlighted on the virtual keyboard, thus the key is being detected by the OS, however, it does not get typed in a text box, for example. I can also press the virtual key on the keyboard viewer with the mouse, and while the key highlights, it does not get typed. Waiting 5 minutes sometimes resolves the issue, and so does putting the computer to sleep and waking it up again. Late 2008 Unibody MacBook Pro. Anyone else? It's extremely annoying as you can imagine.