That pritty much confirms it. You can normally buy cleaning kit from your local supermarket or hardware store. You can also buy them online, for example:
Maplin > CD Cleaning Kit
Hopefully it's just a bit of dirt or dust. Is the PC/Drive still under warranty otherwise? There's little other than cleaning the drive you'll be able to do yourself, as it's a laser device, and even if there was a failed component, such as the DVD Laser Reader (otherwise known as 780nm laser), it would cost as much to replace as a new drive itself.
If it comes to replacing the drive itself, it is very easy to do, only a couple of screws and two plugs, and can talk you through this no problems.
EDIT: Marked as Answered.