Code 43 means that the card isn't responding to the driver nor the os properly and is indicative of a fault within the card. Likely is that your card is experiencing problems. To cut things short start testing your card to probe for the source of the problem.
Bad vram, dead power phase, failed cooling, bad gpu core, and all of these can produce a code 43 error.
Thanks for the reply. I am not that technically proficient so is it possible to explain how I should go about testing the card. It seems that vista simply is overriding the card as I can change the number of colours and resolution beyond that of a vga display. I just have 5 columns of lines running from top to bottom on my monitor which is obviously frustrating.