Unable to open COM port

I have a XBee-PRO-PKG U connected to a Windows 7 virtual machine running on a Mac and an XBee Pro module as the remote device (with a loopback jumper on the main In and Out ports.

When I initially start X-CTU the Modem responds fine, i can read the parameters and write them as well. But when I do a range check it returns a message “Could not open COM port”

Is this a problem with the hardware/software or is it an issue with running everything through a virtual machine?

I think its either the virtual modem error or there may be some error in ur hardware … its not the software one … first of all try it on real com port dont use usb to serial cable and then check ur hardware the output u r giving to the xbee …

Is it true that you were trying to get the XTend modems to connect using a USB to serial connector at one end? If so, did you find a way to resolve the issue? I am facing the same problem and any inputs will be very helpful.