Agreed with Agent_L, call WD and work the warranty first. In the meantime, set up a folder on another computer, and start backing up by copying the contents of the drive to the folder. If the drive shuts off in the middle, go ahead and unplug, wait 30 minutes (for the drive to cool) and the reattach, and continue where you left off. Be warned though that this will stress the drive, so keep an eye on the drive temperature and noise, and intervene if it is alarmingly hot or loud.
In my experience, this type of problem is rarely temporary. It may reduce the lifetime of the drive, or performance may suffer, or both. It may happen tomorrow, or it may take days, weeks, or months to become unusable. Don't wait for this though, noise is usually a sign it is on it's last legs. Backup, buy a new drive, and restore the files. Warranty the bad drive, and if that doesn't work, make sure to mark the drive with a marker, and dispose of it at an electronics recycler. You can have them degauss the drive to remove the contents, as it may still be readable by someone who was determined to get your data. Good luck, and remember to be patient when backing up. Pick a few folders at a time, alphabetically, so you can keep track of where you are.