We can unfortunately only guarantee compatibility with your motherboard, not with any other installed memory. If the original module was purchased a long time ago, the components on it may no longer be compatible with the way components are manufactured today.
On reviewing your account I show that your first module was purchased in 2007, nearly two years ago, and it is not our policy to refund purchases that old. I also show that our Customer Support department contacted you via email on October 7th to offer a resolution. Please check your email and reply to it, and they will follow up on this and take care of your situation.
