sounds like your QS window is going into text mode for some reason.
double check in your trigger preferences that the QuickSilver 'command
window in text mode' trigger is something else?
if you bring up the qs window and it is still in text mode, try
hitting esc once and then type again.
you also may be activating text mode because you're typing too much(!)
i reach address book from just typing as far as 'ad'. try unchecking
the 'switch to text mode if no match found' if that's on too...