Compiling doesn't work always
The compiler for the Portal 2 Authoring Tools doesn't always work.
Sometimes it compiles it correct, like it should, and sometimes, it just does this:
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Running command: cd "c:\program files\steam\steamapps\common\portal 2\bin"
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Running command: "c:\program files\steam\steamapps\common\portal 2\bin\vbsp.exe" -game "c:\program f
iles\steam\steamapps\common\portal 2\portal2" "C:\Program Files\Steam\SteamApps\common\portal 2\sdk_
content\maps\tiletest.vmf"
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Finished. Press a key to close.
It is a nodraw box with just a player in it. Also normal maps wont do it always.
Any idea why it happens, or does someone else also have this problem?
It is really annoying, to be honest. 
Nodraw texture does not block VIS calculation. The compiler cannot do anything with your map.
At the minimum, you need a box with six sides made of solid world brushes (not brush entities), a light entity, and a player to compile.
I strongly recommend you read the basics of mapping before you start. Otherwise, you are setting yourself for tons of frustration.
Vordwann wrote:
He can have the box made of nodraw as long as he uses the face edit tab to texture the 6 inside faces with a non-nodraw texture.
I do not think that will work. You need more than one unit of overlapping brush surface to seal a map.
I had a leak once that I textured just the inside of a glass brush with non-transparent texture, and I fixed it by texturing the entire brush.
Vordwann wrote:
otherwise his compile times will be larger because he'll be rendering unseen faces.
Are you sure about that? Vbsp and subsequent compilers should completely ignore outside faces assuming you have no leaks (and unless you use -noopt). They still exist, but are never rendered and shouldn't contribute to compile times.
Image
Image is in wireframewill make sure that no texture goes overlapped, even if it is nodraw. Also there is much less chance of the leafs being split up unnecessarily.
Medious is right to say that when you full compile that textures on the outside of the visleafs will not be drawn, however if you noclip outside the map it will.
The places where you should be fussed about putting nodraw is in places that the player cannot physically see (but looks like the map would continue in that direction) that is inside the map, and on func_detail's. Seeing as the leaf's totally ignore func_details, all their sides would be rendered. The same for faces that are connected to a func_detail that are world brushes. If you cut brushes correctly, you will also find that there is an ultimate reduction of lighting errors (especially around angled or curved brushes).
So I think it doesn't really have something to do with the map itself, but with the compiler...