I've been getting these weird horizontal lines through my apps and occasionally my desktop. See attached image. I thought it might have been a graphics card problem, but these lines move with the apps even in expose mode. Any ideas? Its driving me nuts. I had this problem before while on 10.4 Tiger and now again on 10.5 Leopard (fresh install on new hard drive). I called Apple Australia and they didn't really offer me a solution. What could be causing this?