I've just purchased a WD My Book Essential 250GB external hard drive.
It's supposedly full plug and play, but it doesn't show up in My
Computer or as an option when I try to save something to that drive.

It will show up in Windows Explorer when I navigate to it using the
drive letter in the address bar, but only until I close Explorer. It
also shows up in Disk Management just fine. I have tried changing the
drive letter, to no avail. It still doesn't show up in My Computer.

I don't have another computer handy to try it on; I just wanted to see
if anyone had any ideas on what is causing this issue and how to
resolve it.

Thanks!