Can't open usb port

I have a weather program that installed fine in Vista, however it can't open
the com port to communicate w/ my weather station. Station is hooked via
USB. Any ideas on how to get that port open? Went thru windows firewall and
added the .exe file to exclusions, turned off my antivirus just in case, and
tried all ports 1-10 to see if the old port doesn't work anymore. Even tried
running the program in Win XP compatibility mode (which it used to work in).
Nothing worked. And is there anyway to tell what USB port the weather
station is hooked to?

Thanks,

Pfaff