How do you keep objects from being walked through?
 

My objects are visible, but you don't stop when you run into them. How do I fix this?

If you can answer this, I would greatly appreciate it.

for 1. you might be using a transparent texture.
it should say on the textures name. see if you cant find the same texture but normal.
if not. you can use "player clip"
will stop the player but bullets will go threw.
if its a wall. just use "caulk"

When I say objects I mean like vehicles and stuff like that.

i use player clip
and then weapon or metal clip

you can make the model solid but then the models origin become a solid.
which I dont like, or recommend.

Oh ok. Sorry for misunderstanding (yes! that's a free post for me! just 50 more now, lol).

Thanks, and good luck with Eye of the Needle cool: