I got a DisplayPort->HDMI cable so I can use my TV as a 2nd monitor and it's great, except it is making close-lid functionality erratic. Sometimes it works as normal and the MacBook sleeps. Other times the MacBook carries on running as normal, windows are open/visible/running on the TV screen after the lid closes, even though the Apple logo on the lid is not lit up. I really don't want to have to unplug the TV and replug it every time, so can anyone suggest a fix? It's a late 2008 aluminium unibody MacBook which I did a clean 10.8 install on.