Purple light on my netbook...?

I have an Acer Aspire One D255 netbook, and there's four icons on the bottom left of it. A lightbulb, a battery icon, some weird icon that looks like a bunch of stacked CD's, and a WiFi icon. Today the battery and lightbulb icons kept combining lights to make a purple light. Anyone know what's up? The normal colors are blue and orange.