I've copied an old project to make a new one as I usually do (editing where necessary), but after some edits the Run-button gets disabled. This has happened twice (first time I deleted the project and tried again), but I still can't say exactly what caused the Run to be disabled. When clicking the drop-down menu to the right of the Run and Stop buttons (top left of XCode 4) I don't see any of the devices or simulators usually available. Instead I see the target project's name, and to the right it says "My Mac 64-bit". Nothing on my mac is called "My Mac", so I'm not sure what this means. Any ideas what has caused this and what to do?