If you're talking about St. Jovite, there are well known graphics glitches
and updates to take care of them. (Don't remember the site, but there's a
link at www.gplpp.com). If you mean San Jose, the only problem I've heard
of is an invisible barrier right near the outside wall entering T1, but we
ran a race there without any of the graphics problems you mentioned, so I
don't know.