S eems prety major to me, crashed game and locked pc causing hard restart.
I hit the 'upgrade' button having selected a design template (one of my own) from the SHIPBUILDING screen (i.e. not from the ship itself) and then proceeded to have a merry dance with removing items, scanners kept reapearing and disapearing as i tried to remove them. Even with less mass space occupied than the space indicator I could not save design, could only exit, eventually I could not exit at all and it locked up.
I am sure I have seen this before in beta. I have the debug err file saved but I can't personally see the log content related to this problem.
Bit of a shame, I was in first level of campaign.