managing graphs



Hello!
>(%i1) plot2d (sin(x), [x, 0, 2*%pi],[gnuplot_term,  dumb ]);

>works as expected in my linux box. 

Does not work in Windows (command line, wxmaxima, xmaxima)

>In png format:

>(%i3) plot2d(sin(x), [x, 0, 2*%pi],
>             [gnuplot_preamble,
>              "set terminal png;set out 'myplot.png'"])$

Wgnuplot.exe crashes and does not respond. When I unlock the file with Unlocker it can be visualized.