Burn to CD and boot from it. Run the memory diagnostic and let us know if you get any RAM errors.
So we can rule out corruption problems. Id RAM is faulty, anything you download is going to end up corrupted.
Next logical step is to perform full surface scan of your primary hard disk and check for bad sectors.
i Will try that tool out,
But if there is any fault with The RAM, then how would win 7, ubuntu, xp & vista work ??
Here are my HDD Test results :