1. Force W2K to deliberately lose all knowledge of the mouse. Go into Device Manager, find the mouse device(s) and disable/remove it/them.
2. Shut down and power off.
3. Make sure the mouse or pointing device of choice is attached and working.
4. Power up and boot (do NOT boot off the CD). W2K should notice there is a new device and want to load drivers. If you can, replace them with the drivers off the W2K CD (or distribution media, if necessary), do not use the drivers already installed.
5. Continue to boot W2K as directed. See what the result is then.
There are easier and faster ways to do this, I know, but this way ensures W2K installs the matching mouse drivers for your installed mouse.