Any chance you have the Submit Action available on the the status itself, as a Optional Action Instance?
Goto your process in Process Designer, highlight the Open status, select properties from the shortcut on the left(Not by right clicking), select (collection) from the Option Action Instance, and see if the action is listed as a Selected Action Instance. If so, remove it from here, as it wouldnt move your process like your design indicates you want.
I've seen the error before while creating a new process, it just isn't fully sparking my noggin of what causes it. I know that what i listed above can cause the issue though.