The issue: My mouse cursor lags/stutters on my Macbook Air. Pre-requisites: iTunes is running. External display (Dell 2407WFP) is connected and active. OS: 10.6.6, iTunes: 10.2.1 I'm noticing a lot of mouse and keyboard lag on my Macbook Air whenever I'm using my external Dell 2407WFP monitor and iTunes is running. It doesn't matter whether I'm in Clamshell or extended desktop, the lag occurs. The only fix is to quit iTunes. If I'm not using an external monitor, then the cursor is perfectly normal regardless of whether iTunes is on or not. I know a lot of people have experience issues similar particularly on other machines with external monitor and mouse lag. If you are on of those can you see if iTunes is running? If it is quit the application and see if the problem goes away. From my experience I firmly believe there is a problem with iTunes, OSX and external monitors connected via Displayport (regardless of whether it is through an adapter or not).