There's a couple of ways of resetting them but my suggestion would be to make an appointment at the Genius bar in the Apple store and get them to have a look. The hole thing rings a bell but I might be thinking of CD drives or something.

They were excellent when we went up there recently with a Mac that had died (first one ever, in 25+ years of owning and working daily on Macs). The machine was knackered, but the chap removed the hard drive and told us hoe to retrieve the data, all for nowt. It's worth a try before splashing out for a new one.