conper

I have geovision 7.05 and i have the following problems. When i add a graphic card on the desktop the picture freeze when they are in big window size. Small size work. They freeze but when i check in view log they were working so the problem is only in preview. One friend of mine told me to use cards under 256mb is that true? I tried ATI x1650 and gforce 7600 and both give me problems. Canyou suggest me what is the problem or tell me a card that will work 100%. Need to be PCI Express.