first and foremost. back up your data if you haven't already done so.
S.M.A.R.T. - http://en.wikipedia.org/wiki/S.M.A.R.T.
usually early warning signs that the drive is going to die however, some give this error due to bad firmware and can be replaced or updated to fix the issue if possible.
in any case, back up your data first. then look up your drives exact model number and see if their is an update available. if their is one available you still risk loosing your data which is why you should back it up first.
always back up your data and have a disaster plan because its not a matter of (if) but, is a matter of (when).