ClamShell Mode not working anymore

does it work with the screen open?

i know that it should work with it closed but if it doesnt work either way you might have a defective cord or thunderbolt port

also for calmshell mode there is a few rules that maybe your not following that you did weeks ago when it worked without realizing it

for instance you need to be plugged into the magsafe charger, have a mouse and keyboard attached either with usb or bluetooth

 

since it works with the lid open its hard to think its the cable

 

Make sure that the MagSafe is actually plugged-in and the light is on. I was having a similar problem recently and I didn't notice that the juice wasn't getting to my MBP. D'OH! I was in the process of figuring out what was wrong when I finally noticed that the light was off...

Since it isn't likely that is your problem, the easiest step to take in your trouble-shooting is to get another cable.

 

Assuming that is Aug or early Sept of last year, yes you can call. You have free support for a year.

EDIT: Correction, it is actually 90 days of phone support.

And, this.

 

You get 90 days free phone support; to extend the time period you will need to buy extended AppleCare. The L.A. Computer Co. and B&H Photo tend to have the best prices.

I suggest posting your problem on the official Apple forum. There is also a Samsung TV forum here: http://forums.cnet.com/samsung-forum/.

 

I believe that included telephone support is 90 days. You are still under warranty so I would bring it in to a store if you can't figure out the cause of your issue.

 

Weird, it's like clamshell mode is switching the external output mode (from something supported like 1920x1080 to something not).

Is it a 15 or 17 with the discreet GPU?

I only ask because that combined with something like gfxCardStatus can create some funky operation if you've tweaked the prefs in gfxCS (I sometimes forgot to re-enable the discreet mode for using my external after running on integrated).