I have been playing around a bit with this error. It can easily be provoked if you just open a new project, give it a name and save it. You don't have to add any elements. Just open the Page manager, and at the top, where in says Index, change that to something else. Then hit Done and save. Go back into the Page Manager and try setting the page name back to Index, and hit Done again...
I happened to do this by mistake yesterday, deleted the word Index and typed the title instead. When I discovered my mistake and wanted to correct it, I had the programme crashing on me, time after time.
So, it seems to me, that if you stay away from the page name of the first page you create, you should be safe. Don't know if any of you have made other experiences.