If upgrading your video drivers doesn't help, you could try
downgrading them. Unfortunately the standard advice to ensure you have the latest drivers simply doesn't always hold true with nVidia, as they have a single driver to cover all their video cards, and newer releases almost always just focus on newer hardware, sometimes to the detriment of older hardware.
I also have a GeForce 4 (Ti4200), and the last good video drivers for my card under Win98 (which I run) was 56.64. Newer drivers invariably make my machine quite unstable.
A quick look at the nVidia forums suggests:
"43.03 was the most stable driver of its era." (
link)
"66.93 WHQL drivers ... or even the good old 56.72 WHQL drivers" (
link)
The latter being in connection with a GF4MX rathger than a GF4, but I suspect the 56.72s are the XP equivalent of my 56.64s so they are probably worth a shot.