The MX 440 is an fairly old card. I am pretty sure there are some functions it does not support that newer cards do (5200 and newer). Whether or not this may be causing the problem is debateable. I have had all sorts of issues with C5 and it hanging at the oddest times. How is your windows paging file (swap file) set up? How large is it? Did you check your DirectX version as well as cideo drivers? Is everything up to date? If not, start there and eliminate the most obvious. Update all drivers and DirectX. I usually dont run W2K on anything having to do with 3D work, but if it's working for ya, great. See if you could find a friend with a more up to date video card you could borrow to test with. The 440 like I said, is very old and lacks a lot of things that more modern cards have. The 5000 series is dirt cheap now and I know from experience that they work very well with C5. Keep us posted on the outcome.