Hi, i have a 2006 Mac Book Pro 15 inches and lately this weird thing started happening. During booting up the screen has some faded bluish lines and when booting sequence is complete all i see is some strange patterns and the closest thing i can think of is that they look kind like a tartan design and nothing else and of course i cannot use the Mac. But that's not all, when i put the OS DVD in the drive and do a restart usually but not always, the Mac starts up and works as normal. Anyone has seen this before? Thanks in advance for any help. Yiorgos.