Wonko's dashboard

I have a vostro 1500 and my warranty just expired a few weeks ago. Two days ago it froze when I plugged in the ac adapter. Upon restarting I received a message stating the AC Adapter could not be identified. Since then it has been freezing hourly when the AC adapter is plugged in. This is similar (though not as frequent) to a problem I had when I first purchased this computer. That time DELL eventually replaced the Motherboard, which seemed to fix the problem until now. Will I need to replace the motherboard again?