The error message is displayed in the attached file WeatherWatcherLive Screenshot 2.
You'll have to shut down Weather Watcher Live before running the installer. Right-click the Weather Watcher Live icon in your system tray and choose "Exit". The installer tries to shut down Weather Watcher Live. When that fails due to permissions, it displays the error message in your screenshot.
I also note that I can only resize the WWL screen downward to a certain extent, which is still too large.
Try dragging the bottom, right corner of the window up and to the right. The window has a minimum width -- and, if you drag the window too far to the left, it'll prevent you from continuing to resize it.