I am a relatively new mapper and am trying to make a map set in the destroyed testchambers. However, when I run my map, Portal 2 runs fine for a second or two and then crashes. I have uploaded the .vmf if anybody wants to take a look at it. (I know there's a whole lot of other things wrong with it, but I'm fixing those.)
In case it matters, my PC has been able to run the official Portal 2 maps very smoothly.

Do you have a player spawn?

Yeah, I do have an info_player_start.

Can you play any other custom map?

I think its funny cause noone has bothered to download the map to have a look.
I'll have a look man and tell you what the problem is.

EDIT: The cause of the problem may be using prop_detail instead of prop_static or prop_dynamic. Prop_detail should only be used by small models that are $unlitGeneric (Also note 'small and 'unlit', which is none of the props you used inside your map. Perhaps maybe that one vine hanging from the ceiling but it would have the same effect using a prop_static). Look at the VDC before using any entity you are not sure what they do: http://developer.valvesoftware.com/wiki/Prop_detail

My game didn't crash after 2 seconds of playing though, perhaps it is a compiling issue?