You realise GTA IV is incredibly easy to run with low settings, especially low view distance? Stop blaming it on his GPU; that isn't his pressing problem.
If it was a GPU problem, it would crash, or lag extremely. It wouldn't simply just not load. Either it actually takes forever to load which might be a problem, or those two zombie mods next to eachother could be doing something. I'm not entirely experienced in the field of mods; but just saying "lul gpu suks" is incredibly unprofessional no matter how you put it.