Thanks for your responses. I don't think it's a heat problem, as I've played other games for long periods of time, and haven't had freezing problems. I have a Real3D video card, which doesn't have an overclocking feature. I tried deleting the preferences file, and rechecking my graphics hardware. I'm running DirectX8.0, and when I check it, it's set for 800x600 monitor resolution, and optimal refresh rate. But when I do the graphics hardware test, the only "can you see this?" message that I can see clearly, shows a resolution of 640x480. And it doesn't show the refresh rate, like it says it should in the manual. I can see the "can you see this?" message for the 800x600 resolution, but it flickers on and off. I'm running Windows, and my desktop is set for 800x600. The CM disk I got is the 1.11 version. I tried the graphics hardware test with the disk as is, and with the 1.12 patch downloaded, but there seems to be no difference.