Problems with Sky tv ???? (one for satellite tv installers)?

When watching tv thru my sky hi-def box I am getting a lot of pixallating (as tho bad weather etc,) also some programmes fail to record, and a lot of the time I get a sign saying ''mini tv signal not being received'', some channels mainly sky's own actually say no Satellite signal being received when in fact if i channel surf there are satellite pictures actually getting thru from sky. Is tjis a box problem or dish problem ??????, thanks in anticipation. mick.