Problem already fixed
In the game installation folder, find the file ww.ini. Open it with any text editor (notepad will do).
Find the following line in this file:
window=(changeScreenRes=true,colourBits=32,depthBits=24,drawIfNotFocused=false,enableClose=false,enableResize=false,fullScreen=true,height=768,stencilBits=8,width=1024,posx=0,posy= 0)
Change values changeScreenRes and fullScreen in it like this:
window=(changeScreenRes=false,colourBits=32,depthBits=24,drawIfNotFocused=false,enableClose=false,enableResize=false,fullScreen=false,height=768,stencilBits=8,width=1024,posx=0,pos y=0)
You can also try to use only one value, changeScreenRes, set to false.
Be careful to leave this line as single... do not accidentally split it in two.
Thanks to Anka and Sio for this suggestion.