Okay, here are some more information: XP10, latest beta. Windows 7. Using the Gizmo version delivered with the recent DC-3 aircraft. No other plugins. I can't give you exact steps to reproduce, but simply do the following -- takes less than 5 minutes: Press FPL on MFD, in 2D display, open ReadyPad. Enter some waypoints, but make some deliberate mistakes in pressing the correct buttons, for example forget to press INIT or forget to press the "Direct to" button on the ReadyPad, then try to correct, also mess around with the inner and the outer knobs both on MFD and ReadyPad, also clear the plan and enter a new one, and close the FPL window, then reopen it. At some point, at least for me, the system will get into a state where it does not bring up the window where you can enter the waypoint, but simply flashes it, with the "USS Nimitz" text in it. Currently, the only solution is that the user has to avoid mistakes (which is not possible, as we're humans and simply misplace the mouse cursor sometimes) and better not change the flight plan once it is entered -- changing it may cause the error and make the FMS unusable.