On my old-ish MacBook Pro (pre-unibody), Quicksilver has been misbehaving for quite some time. I fire the keyboard command to launch it (I like command-space, replacing Spotlight), and it comes up in text-entry mode rather than selection mode. I can hit escape and QS closes, but nothing I can do makes it come up prepared to navigate the objects it knows about.
It used to work just great. But it's a waste of cycles right now because it's completely unable to function as what it does.
I've re-launched it, I've deleted and re-installed it. Nothing seems to help.