Pliler v. Ford, 124 S.Ct. 2441 (June 21, 2004) (no requirement that district court warn pro se plaintiff bringing habeas petition that it could not consider motions to stay unless plaintiff dismissed unexhausted claims, or that if he chose to dismiss the claims, they would be time-barred if raised in the future).
http://laws.lp.findlaw.com/us/000/03221.html