Changing display 1024×768 problem

When I try to change the display to 1024×768 I get an off-center, dark, weird colored screen.I have a one gig AMD Athlon processor. My video card is an NVIDIA RIVA TNT2 Model 64/Model 64 Pro.I’m running Windows ME. I first noticed the problem when Ibought Civ3 and installed it. I tried changing the setting in display window and I get the same thing. Can you help me?