There is a new USB driver available for the VP2 from Silicon Labs. This version (5.0) seems to work much better than 4.4. WD has not hung up since I installed. Mine was hanging everyday previous to this version. Davis told me thay would swap my USB logger for a serial if I continued to have problems with this driver. I’m running Vista Home Premium.
http://www.silabs.com/tgwWebApp/public/web_content/products/Microcontrollers/USB/en/mcu_vcp.htm