The same happened to me. Finding the previous post here, I've tried to
install the latest nVidia drivers from their download pages, but that didn't
fix the issue (it forced a downgrade, which means that they removed the
version I had installed a few days back).
So I uninstalled the nVidia drivers. Unfortunately XP doesn't have a good
default driver for my GeForce 8600 GT based card, but I can now remote
desktop to my machine as I used to before, which proves that indeed it was
the nVidia driver that was the problem.
Now I'm trying to install the much older driver that I sill have on my
system...