Funny thing, I always get those same errors. But I've use sky_gravel_01 and sky_hydro_01. I get that -game thing too.
But I currently ran all the commands and all my cubemaps built fine. But now the truck is shiny all over
Why valve why? Truck tires don't shine!
Your's looks weird though, I think the pink IS from cubemaps not being built, however it also looks like z-fighting, are you sure you don't have 2 floors? Maybe you accidentally cloned one.