Q: I can't use the serial port on my PC now because ActiveSync seems to be using it.
1. If you have already established a partnership with the device and are using Ethernet to connect to the device, you can un-check the box next to "Allow serial cable connection to this COM port" under File, Connection Settings of ActiveSync. You can also do this to temporarily disable ActiveSync.
2: You can also "End Task" on the WCESCOMM process in the desktop PC's Close Program dialog (Ctrl-Alt-Del).