JEEZ MAN THANKS FOR THE AWESOME HELP. We already KNOW it's something to do with that, as that's what a rear wheel comprises of. Where did you get it trued? If it was you LBS you shouldn't be having troubles like that, to be honest. If it was you who did it, or a friend, have a feel of the spokes. The wheel comes out of true much easier when it's loose. Is it deffinately the rim buckling, or could it be one side of the axle slipping in the dropouts? (ie. is the whole wheel wonkey, or is it deffinately a buckle each time?)