It's a Dell with Intel graphics, and i think the focus goes off the active window for an On-Screen Notifier, a little lock on/off symbol that pops up in the lower right corner of the screen, for both Caps Lock and Num Lock. it stays on for 4 seconds, then vanishes, returning focus to the active window. i'm now searching for a way to turn that infernal thing off, but so far, it's controls have not been anywhere i'd expect it to be.