According to your problem description, this may be caused by the virtual machine software after configuring or changing the serial interface. I suggest you try the following steps to solve this problem:

Enter the BIOS setup: restart the computer and press the corresponding key (usually Del, F2 or F 12) to enter the BIOS setup interface.

Restore default settings: in the BIOS settings interface, find the option to restore default settings or similar settings, select and save the changes. This will restore the BIOS to the factory default state.

Disable serial port: in the BIOS setting interface, find the options related to serial port and disable it. This can avoid the problems caused by serial port configuration.

Update BIOS firmware: Visit official website, the motherboard manufacturer, download the latest BIOS firmware version and update according to the instructions. Updating the BIOS firmware may fix some system compatibility issues.

Reinstall the virtual machine software: If the problem persists, please try to reinstall or upgrade the virtual machine software, make sure to use the latest version, and correctly configure the serial interface according to the official documents.

If the above steps do not solve the problem, you may need to further check the hardware failure or seek professional help. Please note that before making any BIOS setting modification or firmware update, please make sure that you understand the operation and back up important data just in case.

I hope my answer can help you ~