Sapphire tech hd 5850: driver issue?

Hi everyone!!

I'm from Brazil, and have been using a SapphireTech HD 5850 for a year now, running all sorts of heavy stuff with it, no problems so far (until yesterday...) Maybe you guys can help me with this one...

I was on the net doing some research for school and suddenly my screen turned black; at the same time, my 5850 took off to its full fan speed for as long as my PC was on until I manually reseted the system through the case RESET button. Sadly, at the very beginning of boot phase the card was still at full speed and my monitor flashed in sleep mode, showing no video signal from the machine. I could hear Windows 7 x64 Ultimate initializing through my speakers, so as Skype and my other programs on startup. No images at all, and card running at full power.

I went to a friend's house yesterday (he has the exact same 5850), and tried the board on his machine. Same issue. We reinstalled his board and everything worked fine, as it should be.

Looks like I've lost my card. Guarantee from the store, (which is an authorized ATI dealer), expired only three months after buying it, and I don't think SapphireTech offers support for Brazillian users.

I was wondering if there's any way to change this situation. I was using ATI Catalyst 11.1, if I remember right, since I had been having fan speed problems while trying the latest drivers. Is my problem driver related? Is there any way I can save my board and also save a big load of cash in the process?

PC specs: Mobo: Gigabyte 890FXA-UD5 Rev. 2.0
Memory: 2x2GB Kingston 1333 DDR3
PSU: Corsair 750TX
OS: Windows 7 x64 Ultimate Edition
CPU: Amd Phenom II X6 1090T

P.S.: All parts are stock configs, I didn't overclock any of them...