I have three USB drives but windows 7 Ultimate build 7068 does not see the 750MB WD essential edition external usb drive. System says its not accecabile. The other 2 drives are fine. (1 WD Essentail Edition 500G and 1 WD Home edition 500GB). The 750G drive does appear in disk manager but I just can't access it. When I boot into windows Vista there is no problem. This is really frustrating me.