Can you check if the Java Web Start version you tried was running under 32 or 64 bit architecture (look at About dialog box)? If it's running under 32 bit, please install Java 64 bit too and run Sweet Home 3D Java Web Start version with it, to check if that version runs correctly too, because I suspect an issue in 64 bit graphics drivers.
To force a Java Web Start in 64 bit, run the following command: