Can't save simulink models - matlab just keeps loading until it has to shut down

We had a couple of quite simple models that we were testing but when we try to save them, Matlab just keeps loading until it informs us that it has run into an error and needs to shut down. Everything seems to work out just fine, until we get to the point of saving the models.

The only thing I could think of having had an effect (but what exactly is something I don't know) is that we had problems starting Matlab in the morning and I did first mistakenly open the license file using notepad, to get the hostname to check if we could get contact with the server, but I then reopened it with wordpad and that problem was solved and Matlab opened normally after that.

The version is Matlab R2013b