I have exactly the same issue. After many, many, many hours of trying to get this thing (grrrr) to work, i though I finally had, then the Windows PC's lost their network mappings, and would not reconnect until I restarted the NAS. I could still ping the drive, and see everything through the web interface. Interestingly, my Macbook had no issues. (Firmware 2.02).
Any help is appreciated....