directpython application bug

[vedran at v-programs.com]

Hello,
I using directpython for making 3d miniature applications,but I have
one problem about directpython.
This is my code for example:

import d3d
import d3dc
import d3dx



device=d3d.createDevice()
groundtexture=d3d.Font(u'my program',30)

...and when I run this code, directpython just open window and after
few minutes close the window


          What to I do?


                                           Thanks!!!