Just when I went to Material mode to check if my textures were fine, half of my mesh seemed to disapear and once selceted the mesh, the half disapeard looked like in Wireframe view.
I tried changing in the Properties Panel and in Camera settings the Clipping End value but it doesn't help.
By the way this happens when I am looking through the Camera and when I am just in 3D view, and also the problem don't appear in Solid / Texture / Render mode.
p.s. There are no Modifiers on them, and this is happening in Cycles Render.