Display Driver Stopped Working - Will Not Reboot / Restart Loop

Graphics card: ATI Radeon HD4870 x2
Running on windows 7 x64 ultimate

I was browsing away and my whole pc froze, with a strange little box around my cursor, although the sound was still working, I force shut down it and restarted and little message popped up saying the display driver has stopped working, I tried multiple things to solve this, to no avail, eventually it kept happening and it got so bad the computer would not start, i tried all of the "F" keys on startup and none worked, eventually i took it to a shop who wiped everything clean and it worked again.

Around 2 months down the line low and behold the same problem happened again, I found a solution and installed a program called driver robot, I used it and installed many outdated drivers, this seemed to fix the problem. For about 6 months, now it has happened again, my computer has now shut down and goes into a constant restart loop, as it is doing this the screens that show up are littered with dots and lines of many colours, I just need workaround on this, preferably without loosing all of my files.