This is not "Arbortext Viewer", this is the application associated with the extension in Windows. In your case, "Windows Picture and Fax Viewer" opens. This is what happens when you double click the graphic. It is supposed to work the following way: when you double click, the graphic opens in the associated software, you then edit it there, save and close the software. After this, when switching to Editor, you see the "Reload Graphic" window, click "Yes" and you see the just edited graphic.
To be honest, I don't think it's the most convenient way - people do not edit illustrations this way and most people anyways have just viewers associated with .jpg and other formats.
In your case, when just need to reload graphics, you do it 1) using View -> Reload Graphics menu or 2) executing 'reloadgraphic' command in the command line (just type "reloadgraphic" without quotes in the Arbortext command line. Make sure it's enabled in Tools->Preferences->Window-Command Line). This way the graphic will be reloaded and no associatied additional windows/application will appear/run.
You can also add a button to the toolbar, but this requires a bit of customization.
Also, do you really need to reload graphics "many times during a work day"?