Serial port 'COM19' already in use

Hi all,

Would appreciate if anyone can share how to solve the problem of com port in use when trying to upload sketches. I realized that I can only upload new sketches to the board by rebooting with the serial port disabled and enabling it after the system restarted. All this is done with the board plugged in (to force the assignment of port to the board? doesn't seem right either...). It didn't work when I reboot without disabling the serial port.

Strange strange strange.

Anyone has any solution or has encountered this problem?

Regards,
Wongster