Prefered network doesn't automatically connect

hi, i recently had a flood and in turn had the power shut off. as of turning the power on, the computer now does not connect to to the wireless network every time, where before it knew my network and was always connected. anyone know why this is, or how to fix it. now i have to click my network every time i open my computer or it wakes from sleep. i have a this problem on my ibook G4 running leopard. my imac does not have this problem.
thanks