"Failed to load the default scheme file. The map views may be missing some virtual elements."

[[Maxx]]

I have absolutely no idea if this goes here or not.
But anyway, my friend has been trying to create a map for Garry's Mod using hl2ep2 textures and CS:S textures.
This happens every time he tries to start hammer/load the map file?
I dunno, he didn't explain in full detail, this happened to me a while ago, but I don't remember how I fixed it.
-disregardimage-

OK, he says he just gets black viewports, and not the error message above, this happens after map load.

I've tried to help him in every way I could, but we can't seem to find a solution, so I've came here.
Anyway, I need to know some possible way to fix this and how I would fix it, because he needs to get this thing opened.
Can anybody here help? If this thread is actually in the wrong section I apologize, never posted in the Mapping forum before and I'm not really clear of it.

[editline]19th November 2013[/editline]

Also, before asking to open the hammer.exe in bin, he told me it doesn't work that way for him either.

[royalbird]

Try opening it through OS:\steam\steamapps\garrysmod\bin\hammer.exe
or you might have to open it through cstrike and make it so it saves to garrysmod :)

[Hyperion01]

This method doesn't work, it gives either TF2, DoD or CSS. After selecting CSS it says that it cannot find the gameinfo.txt, so I put it into the folder it asked (either GMod or CSS gameinfo), but the it just shows up one small window which quickly disappears and the thing crashes. I recommend downloading the Source SDK Base 2013, going into bin and running Hammer from there. However I am not sure if you should use HL2, HL2DM or create a GMod one- I am also beginning with this!