Left4Dead2 Visuals Multihack

I'm also dealing with the "too many indices for index buffer. Tell a programmer" error. I don't have many mods. Definitely not high quality mods that would force this old engine to render way more textures than it can handle, yet this is what happens. I know it's a stretch but, can the chams actually be the culprit? Forcing the engine to render way more textures than it can handle?