PC > HDMI > TV problems

[Valrir]

Hey, I bought a new TV today (Grundig 32" LCD). I was going to connect it via an HDMI cable to my PC, and my computer screen went black (also the TV). Tried to reboot and saw that both screens were showing the boot. And when windows was going to load and login both screens went black again (No signal to the TV) I've tried all three HDMI outputs on my new TV but none of them work.

Would love some help on this!

O/S: Windows 7 Pro
GFX: ATi Radeon HD4670

I've the new drivers and everything, it worked fine with my last 32" LCD TV.

 

[Valrir]

Said I wasnt able to edit so I'll reply instead.

Things I've tried:
Booting with both connected.
Booting with only the TV connected.
I've my HTS connected to the TV so the HDMI ports on the TV are not corrupt. (Tried booting without the HTS connected also.)
Tried switching the ports and trying with my old TV, and it worked on my old TV.