Really annoying problem with Laptop to TV

I'm having this really irritating problem when trying to connect my laptop to my TV.

My laptop is a M11x Alienware Laptop with Windows 7

My TV is a Samsung HDTV

Every saturday morning I play minecraft with my family in the living room. I play on my laptop and connect it to the TV using a HDMI cable, then go, connect to a projector > duplicate screen so they can see what i'm doing through the TV and I can see it on my laptop.

The problem is that duplicate is no longer working - I can only extend the screen.

I've had this problem on and off for a while. I've done things that have worked and solved my problem but then I come back the next week and the problem has reoccured and the previous solution no longer worked.

For example:

one week I updated my drivers and it worked. The week after it broke again and an update was not available.

one week I simply plugged the HDMI lead into a different HDMI socket on my TV and it worked - same again, next week the problem reoccured.

Also as a weird side-note, duplicate works fine on my dad's laptop, and on my other Toshiba laptop. So the problem does seem to be with my laptop. It's just weird how the problem comes back when I haven't changed anything.

Right now nothing will work and I can't get it to fix again. If anyone can help with this i'd be extremely grateful. Thank you.