Originally posted by tjwett
Hope you read this. I am a Mac tech and the only time I see this happen is when the Power Supply is faulty. Unfortunately it seems to happen a little too often. There has been a handful of bad power supply batches released from Apple over the past few years. Stop using it right away and bring it into an Apple Store to have it checked. You can cause serious damage to your machine if you continue to use a bad one. Good luck.