I don't know if anybody else experiences this problem, but when I open my laptop (from sleep) and then try to find a network via the airport icon in the menubar it won't find anything until the battery life indicator is done "calculating". Sometimes that is around 10 seconds... I don't see how they are related, but it always works out that way for me. As soon as it's done calculating the remaining battery time I can click on the airport icon and it will find a network within a few seconds. Otherwise it just sits there searching and won't find anything...