Macbook turning itself off?

Hello all,

I don't really know how to explain what's happening to my Macbook Pro 2011. All I know is that it seems to put itself to sleep for about 30 seconds at random intervals. It only does it when it's plugged in, and I noticed it did it yesterday when I had my iPhone and iPad plugged in. It turns itself off (though the white light that says its on stays lit), and then turns itself back on as though nothing has happened.

Anyone else having this issue?

Thanks!

When did you purchase this 2011 MacBook Pro? If it's been less than 12 months (Applecare Warranty)...take it to Apple to have them look at it.

- Nick