Great it worked!

For others:
You have to unzip the sh3d file, remove the fault <room> element from Home.xml as Emmanuel wrote, and zip it back to sh3d file.

Emmanuel, thanks a lot.
Matus

Hi,
I have problem opening file that I edited with AdvancedEditing plugin.

I tried to open it with java console, and here is the error:

java.lang.IllegalStateException: Room points must containt at least two points
at com.eteks.sweethome3d.model.Room.<init>(Unknown Source)
at com.eteks ...