I had the same problem after updating java.
I deleted java and went back to the recommended java version and everything went back to normal.
see this page for the correct java version for your archicad:
OS X won't let you install an older version of java so you have to manually delete it.
To do so open and terminal and enter these two commands:
sudo rm -fr /Library/Internet\ Plug-Ins/JavaAppletPlugin.plugin
sudo rm -fr /Library/PreferencesPanes/JavaControlPanel.prefpane
then install the correct java version given by the first link.
you should then be able to save you file as usual.