I've a Macbook Pro 2.2 (2.16Ghz 3Gb Ram ATI X1600) with SL-10.6.6 and some days ago the display problem started also to me.
I was playing with Ableton live an intensive set, cpu was about 80° for a long time.
At some point the audio continued to go but the monitor started to display an oblique pattern of pixels and the system freezed.
So i've restarted my laptop and the oblique pixel patterns appeared immediately on the boot, and after the apple logo, with the loading circle finished his cycle, an empty gray screen, without pixels, freezed on my laptop, snow leopard wasn't loaded.
Then i've tried to reset PRAM and SMC, then i've started the laptop in safe mode with shift button pressed.
Snow leopard loaded correctly but always with these oblique pixel patterns.
In the meantime i've checked the temperatures that were around 48-50° for cpu and gpu.
I've restarted in normal mode and the oblique pixel patterns disappeared.
So i've downloaded the Maxon Cinebench to strees the cpu to see if it is an overheating related problem.
I've started the cinebench test and in around 3-4 minutes the oblique pixel patterns reappeared.
I've re-did the first procedure, PRAM
SMCSAFE BOOT, but this time without success.
I thought then to replace the termal compund, i've disassembled the laptop, cleaned the logic board cpus, applied the new silver thermal compound and restarted.
Same temperature and same behaviour, the oblique pixel pattern still remained.
The only working boot was the safe one, that of course included also the oblique pixel pattern.
So i've booted in safe mode and reverted back to 10.6.0.
The system now boot also in normal mode, but the oblique pixel pattern still remain.
I've deleted the X1000-X2000-X3000 extensions into the system library and i've done a permissions repair but all without having success.
To be clear, i've done also the Apple Hardware Test with the OS dvd, and also with the deep test mode the result was that no problems were found on the machine.
At this point i don't know more what i can do and i suspect that the only thing can be a fried X1600 Gpu.
This will need a logic board replace that @ifixit will costs 599$, around 460€.
Someone experienced my same problem or have to give me some advices?
Thank you all!
PS
I'm thinking also to buy a new imac 27, but as it have also an ATI video card i'm a bit afraid to spend around 2000€ for a machine that if stressed with high intensive tasks could go in hardware breakings.
Message was edited by: RiccardoRics