Crashing when I select Tracker option

[GoldenSun]

I have a script that runs fine with HMD, Full screen and stereo selections. But when I also select tracker option. I get the following error.

winviz.exe has encountered a problem and needs to close. We are sorry for the inconvenience.

I have about 10 of the pic files loaded in the environment. so I have 10 sets of follwing:

screen1 = viz.add(viz.TEXQUAD)
screen1.translate(0.8, 1.500, -1)
screen1.setEuler(90, 0.0, 0.0)
screen1.scale(0.8, 0.5, 0.5)
image1 = viz.addTexture( 'pot.jpg' )
screen1.texture(image1)

When I remove all or some of them.. the program works with the Tracker option.

Do you know why? Is there something I can do to fix it? is there another way to post pics in the environment?

Thanks.