I have a MacBook Air end 2011. I have connected a "mini display port to HDMI cable" to my TV. The TV is recognising the Mac but the TV screen has the generic Apple (milky way) screen wallpaper and only three of my files displayed ...VERY ODD!! My regular desktop is not displayed on the TV? I suspect there is something in the Mac preferences/settings I have to adjust... but what?? Anyone help???