The nonpaged pool error generally indicates a memory leak in something. Unfortunately, they're not the easiest things in the world to track down.

It's been ages since I had to do this, but I used the Driver Verifier tool from Microsoft to do it -- you need to figure out which driver or process is allocating nonpaged pool memory but never freeing it.

I'm afraid I don't know if there was anything similar for NT 4, and even if there was I'm not sure how much good it would do you -- you're unlikely to find the developer of the problem component still working on NT4-compatible versions.