Jasper,
Although I tend to avoid doing this, I once again saved a model with the current set-up. If I do that and want to open the model again, it does open the model diagram, it also opens the interface, but then it opens the welcome screen and goes into what looks like an infinite loop. At some point it opens the welcome screen and if I click that away, it askes me if I want to close the program or wait for the process to end (it never does, so I tend to close the program)