Thank you so much for this extensive list of things to look for.
I can eliminate one: external USBs are not the cause - I disconnected all of them already.
But I wil go deeper soon. It is my mom's laptop living ~100km away.
Hi, I have a Laptop running win10 (german) and since some days with no immediate trigger a sound was played and it repeats about every 2 seconds.
I checked it is a system sound.
Fist I suspected a loose USB connection and had a look at the devicemanager.
This shows its device list, then the...