Tried opening a third plan. No application icon on the task bar at all. Had to use Alt-Tab (or Windows Task Manager) to switch to the 'missing' instansiation of AP. Closed the third plan document (File→Exit). All instances of AP crashed to desktop. No log recorded.

Tried restarting AP (whilst watching the Task Manager). Splash screen is displayed then hard crash. Occured twice before successful start up. Always a bit suspicious of the memory state after a hard crash so will be rebooting this machine before doing much more testing.

Had one instance of opening three plans and all the task bar icons and windows disappeared. All three AP instances were listed by Windows Task Manager. Used 'Switch To' to regain access.