The PC is a Fujitsu Esprimo P910, Intel Core i5-3570, 8GB RAM, Windows 10 Pro Version 2004 Build 19041, 572. QB64 last version 1.4 win-x64.
Just now I have tried it again, all points, no crash. When it crashed: QB64 suddenly became huge and didn't react to anything, and could only be closed via the task manager or by closing it in the taskbar. Four reboots, but the problem was persisted. I have no idea what might have happened.