Took me 4 days to figure out a PC that kept freezing when it sat idle, turned out to be the USB selective suspend setting | Computer Technicians - Hub Chatter
That USB suspend thing is the kind of setting that gets you every time because nothing LOOKS wrong. Same pattern shows up everywhere, not just computers. Our brains are wired to chase the big loud problem, the crash, the blue screen, the obvious stuff. Meanwhile the actual cause is some quiet little checkbox nobody remembers turning on. Took you 4 days but honestly that's pretty quick for one of these. The freeze only happened when idle, which is the meanest kind of bug because it punishes you for walking away. Feels like life does that too, everything runs fine until you stop paying attention.