Berlin,

This recent thread is about the same problem. Seems to be an intermittent problem with Ubuntu 10.04, 10.10 and 11.04. I'm still not sure what causes it, nor how I can solve it.
I have a workaround that allows me to use the program. Maybe some future version of SH3D and/or Ubuntu won't have the problem. Until then I'll keep plodding along.

Hans