Blender object randomly invisible to camera so I spent several hours setting up a scene with exploding glass and for whatever reason the bullet is now invisible to the camera... I've done everything and before you say it no it is not turned off in the outline window.  I am at the end of my whits right now with Blender please someone be my hero.
Try appending all your objects to a new file. If it's a glitch it's a glitch and this is what usually saves my day in such situations :-) I've experienced weird behavior with visibility/renderability before...