Harddrive Warning Message

On boot up, I'm getting a Text Warning Message (while still in the DOS
environment) that says my Harddrive may fail. It says to backup my date on
my slave drive due to failure that may happen. Then I have to press F1 to
continue and boot.

Specifically:
It's the drive S.M.A.R.T. system informing me that trouble is heading my
way.

So I ran Norton Disk Doctor that found nothing. I've defragged everything
with no issues.

How do I know that this message is correct?
What do I do?