I have been having an on-going issue for some time with my external WD My Book. There are times when it is not being recognized by Windows 7(pro). It has three interface options (fire wire, esata, and USB). I have tried all three at one time or another, finally settling on the eSATA interface...
backup storage
bios detection
device intermittency
esata
external hard drive
firewire
hardware recognition
pchangs
peripheral devices
shutdown problems
storage issues
troubleshooting
usb
usb interface
wd my book
windows 7
windows issues