USB - serial adapter com port assignment changes

[wbanz01]

I have a Windows application which communicates with a weather station through a com port. I have installed Prolific Technologies USB-Serial Driver which comes with the USB-Serial adapter which comes with the weather station. The Weather software configuration assigns a Com Port number.
However, whenever Windows is restarted (Vista running under Parallels 7) the USB - Serial Adapter is assigned a new Com port number and the software cannot communicate with the weather station.
Is there a way I can define a fixed Com Port number for the USB-Serial Adapter?
Thanks.

[JanneT]

I have same problem with Star TSP100 receipt printer connected into USB-port. Any way to "lock" USB port numbers?

[mikedparallels]

same problem - would like to assign single com port that corresponds to the same com port that is identified in the windows virtual machine and would like it to stick