Ed,

In case you are using Ubuntu, (un-)installing Java isn't very difficult.

1 - Go to the Software Center and uninstall IceTea Java.
2 - Go to the Sun website and download Java. (I am using 7.)
3 - Go to this page and follow the instructions for installing Sun Java.

Switching from IceTea to Sun Java solved some problems, and SH3D now runs without any problems.

Hans