the wireframe look stable right?
have you weird stuff in your post process material?
are you working in a super giant size? or super far away from the 0,0,0, of the world ?
the last thing i could do is blame , drivers , memory , GraphicBoard.
Try creating a new level with one of the object that goes crazy.
in the level it works? ensure normal size and normal position.
try also choosing a material of the editor like grid material.
let me know