I hate to hear about iBooks that choose to act up. I've only ever had one problem with my Combo drive and that turned out to be a software issue.
As your machine is only a couple of months old, it should still be under its' Apple Warranty. I would therefore advise you to get on the phone to them and see what they say. The numbers should be somewhere amongst the bumf that came with the machine.
There's no point in me trying to advise you when it could be any number of things. And if the problem is major you'd be as well getting the big boys in to sort it!
Bear in mind though, if you are trying to copy comercial disks (games, applications, etc.) these are becoming increasingly copywrited. Not that I'm suggesting you would ever break the law. 😉