I have a 2TB My Book Essential external drive. I started using the backup software for it and it was working OK.
Then I decided to Copy and Paste my photos onto the drive so that I could transfer them to my wife’s computer. I must have been a bit careless unplugging the drive i.e. not reading the instructions. The photos transferred across to the other computer, but when I plugged the drive back into my computer I started getting the message “Windows delayed write failure”.
I discussed this with a colleague and he suggested I run CHKDSK /r on the external drive.
It worked for me. The drive is working well for me now, but I am only using it to Copy and Paste files for backup because I find the WD backup software slows down my (elderly) computer too much. 
