My own 4TB MyBook is a bit skittish at times.
First off, it's not a very peppy device.
Second, I sometimes lose the network connection to it when downloading directly or transferring files. This happens with both Windows 7 and Windows 8.
Third, it seems to max out my network quickly when I transfer data to it from a local hard drive folder, especially if the file being transferred is a large file such as a zip or iso. I think this issue is not a network problem per se, but instead a function of the slow disks inside the MyBook.
I'll continue to use it for "nearline storage", but I'm not fond of it and truth be told, I won't look at another one in the future. I'll build my own NAS with separately purchased hard drives of my own choosing.