An error in the way Windows handles Page Files in Windows 2000, has been carried through to Windows XP. Symptoms: A Windows 2000-based computer may stop responding (hang) when you use an Accelerated Graphics Port (AGP) program such as Ziff Davis 3D WinBench 2000. This behavior may occur more frequently depending on the computer's processor, memory, and graphics configuration. This problem is known to occur with Nvidia GeForce 256 and Matrox G400 video adapters on computers with AMD Athlon processors. This issue is not specific to any particular video adapter type.

This error is also existant in Windows XP, although personally I have not seen any issues, but M$ says its still there... tends to happen to people with lots of RAM.

Windows 2000 KB Article: Q270715

Windows XP KB Article: Q321938

The fix can be located here