Power Cord Light is Orange, not Green

I'm having some sort of problem with my MacBook Pro. First, it started botting into Setup Assistant, then it wouldn't start at all. I talked to a "Mac Genius" at the local Apple Store, and he thinks I have a corrupt file structure. He suggested I erase my hard drive and reinstall Leopard. However, I'll probably just copy a clone back from my external hard drive. I'm pretty sure it's OK.

Anyway, I just noticed another problem. When I got home and set my computer back up, I plugged in the power cord, and the little green light came on...but it quickly turned orange. Isn't it supposed to shine a constant green as long as it's plugged in? If so, then what would cause it to turn orange? Could this be the source of all my problems in the first place, or could it be a symptom of a hardware or software problem? I'm confused.

Thanks.