I suggest:
1.Go to C:\Users\Username \AppData\Roaming\eTeks\ and rename the folder "Sweet Home 3D" to "Org_Sweet Home 3D" then launch the SweetHome3D application and try to add models. If it does not crashes then the problem is any of your imported furniture model is too big or buggy.(Rename folder back to load your old preference and models).
2.If it still crashes then update ATI driver.
3.Re-download and re-install SH3D.
4.Try Java web start(Requires Java runtime latest) instead of installer.
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