Really really strange. [:(]

Did you ever succeed to save something with Sweet Home 3D?
Can you try this, please:
- Open Java Preferences in Applications/Utilities folder
- Click on Advanced options tab, and select Display console option
- Run Sweet Home 3D Java Web Start version proposed in Download page
- Try to reproduce your problem by saving your document
- Copy/paste here the text that will appear in the window console that will be opened with Sweet Home 3D. It should be something starting by Exception in Thread...
If no exception is displayed in the console, please describe the exact minimum steps of a reproducible test case.
Thanks for your help.