You probably mapped the texture to your sphere by mistake. Make sure tha you assign your sphere the lambert 1 texture so it doesn't do that. Otherwise, it could be a graphics card issue. Post up a pic so we can see exactly whats goin on.
"The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man."
George Bernard Shaw - Man and Superman