In Windows, there is a settings file named:
C:\Users<username>\AppData\Roaming\Dirac\Dirac_Live_Processor\DiracLiveProcessor.settings
The file should have the following line:
<VALUE name="windowPosition" val="729 371 800 400"/>
Delete the entire file called “DiracLiveProcessor.settings” and then log in to the Dirac Live Processor again. The window should now be restored to its original size.