On my PC I also use Ubuntu 10.04 Lucid and SH3D v2.3. It's the most recent installer version which you can download here. Clicking Help --> About in SH3D shows that I'm using Java 1.6.0_18.
On my PC it works flawlessly.
As I'm 100% non-technical I can't help you with your log files. Maybe Emmanuel can distill some higher truth from it.
In case it's of any use, I attach a screen shot of Synaptic Package Manager that shows which Java-related programs I have installed.
Hans
