Looks like the USB connection is causing interferrence with the wireless signals.
have a read of this http://discourse.weather-watch.com/t/31524
Make sure you are using a good quality USB cable with the ferris iron core at the end. You may need to spend some time finding a right location for both the sensors and the console where the signal strength is best.
There also a number of discussions on improving the antenna for the WMR100 under the station equipment section.