I have found this morning that if I right click on the start button and select 'Explore all users'. The icons in the window are all flashing on and off. I can stop this by reducing the size of the window, either by clicking on the box in the top right hand corner, or by dragging the window to a smaller size. This has never happened before. The computer is running absolutely normally otherwise, and is like lightning. I have run a system file check in sfc /scannow. I have run check disk. What on earth can be causing this to happen? I run XP Home.