NV4.SYS is apparently the "Windows Neptune display driver for NVIDIA".
Have you tried booting into "Safe Mode" and updating the drivers for your video card to the latest release?
Also, you may need to fiddle with the BIOS settings. There is a Microsoft Support article that points out that you may have problems: "if you have a display adapter that uses the NVIDIA chip set and the basic input/output system (BIOS) on your computer does not have an interrupt request (IRQ) assigned for the display adapter. ".
The article is at: http://support.microsoft.com/. Search on article: Q268467
Note: To start in "Safe Mode", see these instructions taken from the Win2k Help system:
To start Windows 2000 in safe mode:
Click "Start", and then click "Shut Down".
Click "Restart", and then click "OK".
When you see the message "Please select the operating system to start", press F8.
Use the arrow keys to highlight the appropriate safe mode option, and then press ENTER.
NUM LOCK must be off before the arrow keys on the numeric keypad will function.
Use the arrow keys to highlight an operating system, and then press ENTER.
Notes
In safe mode, Windows 2000 uses only basic files and drivers (mouse, monitor, keyboard, mass storage, base video, default system services, and no network connections). You can choose the Safe Mode with Networking option, which loads all of the above files and drivers plus the essential services and drivers to start networking, or the Safe Mode with Command Prompt option, which is exactly the same as safe mode except that a command prompt is started instead of Windows 2000. You can also choose Last Known Good Configuration, which starts your computer using the registry information that Windows 2000 saved at the last shutdown.
Safe mode helps you diagnose problems. If a symptom does not reappear when you start in safe mode, you can eliminate the default settings and minimum device drivers as possible causes. If a newly added device or a changed driver is causing problems, you can use safe mode to remove the device or reverse the change.
Hope this helps!
JS