My observations:
When LFS is in window mode (I mean, it is supposed to be), the window does not become visible. The windows upper bar is visible for a short while, then it disappears. LFS.exe is shown in task manager
If full screen is used, LFS appears normally. However, when switching to windowed, it disappears, but this time stays visible in the task bar. Clicking on it appears to activate it, but LFS doesn't appear (like it's minimized). Right clicking and choosing maximize makes the window appear and from there on everything is normal.