Could you tell me the size of the saved file (select it and type Cmd + I shortcut) ?
I looks like that the homes you created are incorrectly handled. It's the first time a user reports this kind of issue, but let's try to fix it.
Please launch the Console application (you'll find this application in Applications / Utilities folder), then run Sweet Home 3D, draw a few objects in it, and save the home.
As you got an error, there should be something in Console window called a stack trace which looks like this :
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Exception in thread "AWT-EventQueue-0" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
at com.eteks.sweethome3d.swing.ControllerAction.actionPerformed(ControllerAction.java:73)
at com.eteks.sweethome3d.swing.ResourceAction$AbstractDecoratedAction.actionPerformed(ResourceAction.java:159)
at [...]
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at com.eteks.sweethome3d.swing.ControllerAction.actionPerformed(ControllerAction.java:69)
... 39 more
Caused by: java.lang.RuntimeException: Error
at com.eteks.sweethome3d.io.HomeFileRecorder.writeHome(HomeFileRecorder.java:61)
at com.eteks.sweethome3d.swing.HomeController.save(HomeController.java:1059)
at com.eteks.sweethome3d.swing.HomeController.saveAs(HomeController.java:1041)
at com.eteks.sweethome3d.swing.HomeController.save(HomeController.java:1026)
... 44 more
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Could you forward that error in the forum, please. It will help me a lot to find where the problem comes from.
Thank you