All power saving is turned off in the BIOS and in the OS. I have run multiple trouble shooting programs on the machine over the course of 24 hours at a time. I have changed the CPU's. I have changed the drives and even broke the RAID. Nothing helps. After about a week, the thing locks up and I have to cold boot it. Then, when it comes back up, no error messages and nothing are in the log. There is no software running on it. Just the OS and virus software. I did try turning the virus software off. Any ideas or things I can check?
You've done a lot of the right things. I'm assuming that you haven't been able to associate the lockups with any particular evolution such as running a particular application, performing a certain test, running a backup, and so forth. If it occurs at approximately the same time each week, or at the same time of day, I'd be looking in that direction.
Have you done all the hardware related hygiene checks? Latest firmware for BIOS, RAID controller, video, etc? Absolutely the latest Win2000 drivers for all peripherals?
You changed the CPUs, but did you change the motherboard? Do you have any other machines of the same make, model, motherboard, and peripherals? What's different between them as far as drivers and applications? If nothing is different, you must have a hardware issue of some sort.
Are there any symptoms before the lockup? Slow performance? Paging file thrashing? If so, you could look for a memory leak in an application or driver. Run Performance Monitor in logging mode and check the memory counters.
If you absolutely can't tie the lockup to a specific driver, I'd suspect a subtle hardware problem. I've had lockups like this. One time it was a power supply that would spike and lock the system. Other instances came from PCI bus timing issues and resource sharing. You'll need to work with the hardware vendor. Don't let them put you off that it's a software problem until they've agreed to change the entire machine and the problem persists.