Really weird one this. Have had this mac for well over a year / have been using macs intensively for video and sound work for over 5 years - never seen this. Every 10 minutes or so my application switcher pops up, interrupting my work. Has anyone any ideas why this might be? Was thinking it might be a rare occurrence of a Mac virus but then I thought possibly not. Is there a button etc. I might have pressed by mistake?