I'm getting an invalid device error when I try to create my command queue using my second video card. I have two Radeon HD 5800 series video cards (crossfire is off) and I only get this error with the second card. The program runs just fine on the first. I've looked into the AMD control center on my pc (windows 7 operating system) and it says the second cards adapter is disabled. How do I correct this? If it's just a matter of enabling the card adapter how is that done? I've looked around a bit and haven't had any luck with this.