What problems might arise using a 45 watt power adapter on a MacBook that's supposed to use a 60 watt supply? I've looked around, and it seems that a _higher_ wattage won't hurt your computer, but a lower-wattage adapter might cause "operational problems" and these are unspecified. My sister in law isn't too bright. Her adapter "broke" so she bought a new one from "a guy" and apparently it's not the right wattage. I told her when it happened "Go to FutureShop, they sell them there." Of course, now they only sell the new-style ones. This is one of the older ones with the little flat white plug that has an amber or green light. She needs a new battery too, but that's easier to find. Sorry, I don't have the exact model/year of the MacBook, and it would pointless asking her. She'll have to bring it over (just so I know what battery to get). I know she's still on 10.5.8.