[yellow box] prop loading pro(b/p)lem, the viewradius

Hello, I'm just a mapper that started yesterday, and have encountered a problem in the prop-library of Hammer, I have encountered the same problem on my map itself, but there it wasn't a great problem at all, it is that props are BIG YELLOW BOXES untill I get really close to them, I can't use the prop library like this! its impossible! there's just big yellow boxes all around, and only if I get EXTREMELY close, the prop is vieweble (is that even a word?) Help please!

thanks in advance!