In a products liability case arising from a tractor roll-over accident, summary judgment for defendants is affirmed where: 1) dismissal of strict liability failure to warn claims against defendants was proper as plaintiff failed to show a warning would have altered his behavior; 2) the district court did not abuse its discretion in excluding plaintiff's expert's opinion, leaving him without the requisite expert testimony to establish causation on his defective design claim; 3) as the prior claims failed, negligence claims with a higher threshold of proof also failed; and 4) a derivative loss of consortium claim likewise failed.