Hi I've got a 23" ACD which is almost 3 years old (The AppleCare expires in November). The problem is on certain screens, the picture flickers (eg in Photoshop (on PC), when the canvas isn't full screen and you've got the grey background, the grey background flickers). On occassions they whole screen will flicker but not as often. I thought this might be due to me using a cheap KVM switch but I'm puzzled that it's only intermittent and if it was the KvM switch it would be constant. Does anyone have any advice? Should I take it back to Apple while it's still under AppleCare?