Thunderbolt port HDMI issue

Hi,

I have been using my two week old Macbook pro with an external Samsung monitor Via a mini display to HDMI adaptor, this has been working amazingly and pumping the audio out with it FANTASTIC...... Until just now! When i connected my screen to the external monitor (the Samsung screen) can not find the correct signal, now and again the screen will flash up with my desktop flicker and then keep searching for a signal.

Why has this stopped working?? I did some tests to try and find the fault, here are the results

1. Try a different HDMI port on the Monitor RESULT nothing changes

2. Try a different HDMI cable RESULT no change

3. Plug a different device (PS3) in to the monitor using both HDMI cables and trying both ports on the monitor RESULT it worked perfectly.

4. Use a DVI to HDMI cable to test the mini display adaptor RESULT Singnal sent perfectly.

So form this its not the TV and its not the cables or adaptor, it must be the computer sending a bad signal or the wrong resolution or something.

Any ideas this is driving me mad...

Oh an i also tried tuning everything on and off again.

Thanks