The second file you sent has the same issue (a file full of zeros).
Sweet Home 3D always run with Java, and if you didn't notice, this is probably because you use Sweet Home 3D installer version which embeds a private copy of Java. Please, choose Help > About Sweet Home 3D menu item and report here the versions you use, like in the following capture which shows version 4.3 for Sweet Home 3D and 1.6.0_45 for Java:
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Emmanuel Puybaret, Sweet Home 3D creator
