My late-2010 MacBook Air is back, pristine and in full working order after a visit to Apple’s workshops. I took it to the Covent Garden Apple store on January 11 because I had noticed a ripple effect on the screen, a little bit like a constantly moving wave. The problem was diagnosed as analogue interference and a new screen was needed. Although the computer is 14 months old, the lid-and-screen unit was replaced without charge under the Apple Care warranty. If I hadn’t had Apple Care, the cost would have been £244. Has anyone else experienced a rippling screen on a MacBook Air?