If you see this error message at the start, please follow the instructions below:

Click OK to close the error message.

Click on the CNCSimulator Pro icon in the taskbar.

Find the small CNC Simulator Pro window somewhere on your screen. It will look something like this:

Move the mouse cursor over the lower right corner until it changes to diagonal arrows.

Left-click and drag until you have resized the window to its desired size.
Exit the simulator and restart.