Thank you auggy.
I did download the UiPath Studio software sometime in the middle or end of February as I was attending a brief introduction course on robotic process automation. I have not been launching the software after the one-day course.
On 12th April, I installed 2 VMs using the Hyper-V Manager, with Windows Server 2019 OS installed. The Reliability Monitor showed poor stability since then, and I uninstalled the VMs.
I re-installed the VMs about one week later, but had no time to use them until now. So I supposed they have nothing to do with the current issue.
The Cisco Packet Tracer v8.0 (64-bit) was first installed probably on 28th may. Because of the crashes, I uninstalled and tried it out with v8.0 (32-bit). It didn't help.
I later installed v7.3.1 instead, the problem persisted, even when I did not use it for a couple of days.
Feel free to let me know if you need further information.
Thank you.