The reason for this is due to a problem associated with the VIEWER program. When a TRANSYT run is completed the VIEWER program is launched automatically. If before carrying out a TRANSYT run you already have the VIEWER running AND MINIMISED and you answer “Yes” to “Display in active Viewer?” you may get this problem. N.B. no drastic action is required – all that is needed is for you to task-switch (i.e. use alt-tab) to switch to the VIEWER icon on the task bar. Then immediately maximise the VIEWER. You will find that the VIEWER has successfully loaded and displayed your latest TRANSYT run output. If you experience this problem it can be avoided altogether simply by not minimising the VIEWER – just taskswitch back to TRANSYT when you wish to leave the VIEWER running.