[SQ4 B3] Main windows "dies" after a few hours of strategy generation

I´ve had it 2 times now that SQ4 was running during the night for ~10 hours and each time I wanted to check the results next morning, the main UI window would not rebuild itself when clicking on it. Only the border of the program is showing up. It also did not hang up, the CPU usage is still at ~80% and RAM usage keeps changing and it is generating new files on the hard drive for the new strategies it generates. So it seems it is still generating, but the the UI won´t come back on at all.

The attached screenshot shows how it looks like when trying to switch from Notepad to SQ4. The SQ4 border appears, but the window with the content won´t come up at all. All of that while SQ4 is still perfectly responsive in Task Manager and, as I can see by the files on the hard drive, is still generating strategies.