will not open the serial port montior for my arduino nano

I can upload code just fine, but the serial monitor will not open it just says:

**** Failed to open the serial port COM4 ****

Serial Monitor works in Arduino IDE, and restarting does not fix the problem.

You usually get this error if you have another serial window open on this port. I assume COM4 is indeed the port number for the nano. Do you mind showing us your .ini file?