well i just did the basic install, got the 100% or whatever the file was called that was linked of the track db, installed it, ran gpl - works beautifully. it's just that i killed a bunch of my cars trying to go around just once lol. so the installer works as it should and the track itself seems to be fine, too.
i didn't install any other update, patch or whatnot, see below. that's what i got in my trackfolder after installing.
so i think the package as such is fine. btw what's your gfx card specs? you said you're running w98, so i'm thinking maybe your box is a little on the old side and maybe, just maybe, there's a texture/memory issue. like this track is using textures of a size to big for your box to handle. have you tried kenny's update linked somewhere above? he's done heaps of voodoo updates and maybe this is just what your box needs to run, as i doubt this track includes any type 7 mips that would require the v2 rasterizers.
if possible maybe try switching between ogl, d3d and software renderers (v2 too, if possible).
on a sidenote, i had a similar issue with brands hatch. i think i never had an update for it, but for some reason it wouldn't run with some mods, popping the same error you got, now i just renamed the folder that wouldn't load and re-ran the installer and voila brands loads in the mods - will check what was different between the 2 directories.