My computer "freezes" after opening Serial Monitor

Sometimes when I open the serial monitor (or run pio device monitor), it shows error that says:
Disconnected (ClearCommError failed (OSError(22, 'The semaphore timeout period has expired.', None, 121)))

After that, my onboard notebook keyboard stops working and my USB mouse stops working as well. Therefore, I am forced to restart my PC by holding the power button. This started happening today and never happened for the past 3 months of using this notebook.

Any experience with this or any ideas how to fix this?

Thank you so much

This isn’t an error I’ve come across, so I “DuckDuckWent” and this lot came up:

Disconnected (ClearCommError failed (OSError(22, 'The semaphore timeout period has expired.', None, 121) at DuckDuckGo))&t=raspberrypi&atb=v375-1&ia=web

Anything helpful in there?

Cheers,
Norm.