I have had the same simlar situation, WIN7 64, except that my mapped drive was fine, and then presto it stopped working with the mapped drive. It was fine by going to the IP address, but not the share name.
I’m RMAing the drive to WD, this week. For this issue, as well as another where the lights in the front, are not on. Even when transmitting data from the drive. I have reset the drive, as well as pushed the button to reset. They wern’t lit, for 2 days and then on Saturday night Poof, they turn back on.
This is enough. RMA, is what I was told to do from the Tech guy that I called on Thursday/Friday.