Do have access to another computer with Maya? If so, try the image plane method as discussed, adjut alpha if necessary... I'm starting to lean toward Pony's thought that it could be video card issue, perhaps an overlay problem. If that is the case the Alphyflyte's method may be your only option. As for turning them on/off in persp, if you move the planes far enough out you should be able to get an unobstructed view. Moving them back won't affect the appearent size in the ortho view.