It could be one of several problems. There are several threads currently active about such problems. Try reading them and following the advice you find there.
On Sep 4, 8:08 am, zebbie <[email protected]> wrote: > I recently upgraded my Mac to Snow Leopard, and Quicksilver worked > without major problems (I only use it for basic app launching). Today, > I tried to upgrade to the latest version b56a7, but I can't get it to > activate, neither with hotkey nor by clicking the Dock icon. I > restored the old Quicksilver from Time Machine and it works again as > expected. What is wrong?
