I can now confirm that the crash you are getting is caused by the same issue that is fixed in Modo8. In summary, when you close the scene, Modo is leaving the workspace allocated in memory, so when you next create an Octane Override (or even open the Schematic) you get a halt to Modo because the new workspace is already in Modo memory. This only happens if you close the scene with the Schematic CLOSED. So until I find a workaround, leave the OctaneRender Setup panel open (off the edge of the screen if needed) if you close a scene. Searching for a fix now....You right! This is a bug that that also impacted deleting Overrides, which I escalated to the Modo devs, and they have put the fix into Modo8, but that doesn't help us right now. I will find a workaround (as was done for deleting Overrides).
Paul