Refresh SDK-tools and restart steam?
Have you tried clicking on "Reset Game configurations"?
In your source sdk/bin directories
you can found a GameConfig.txt
if not, refresh SourceSDK content or make it like the following :
"Configs"
{
"Games"
{
"Half-Life 2"
{
"GameDir" "c:\program files\steam\steamapps\\half-life 2\hl2"
"hammer"
{
"GameData0" "c:\program files\steam\steamapps\\sourcesdk\bin\halflife2.fgd"
"TextureFormat" "5"
"MapFormat" "4"
"DefaultTextureScale" "0.250000"
"DefaultLightmapScale" "16"
"GameExe" "c:\program files\steam\steamapps\\half-life 2\hl2.exe"
"DefaultSolidEntity" "func_detail"
"DefaultPointEntity" "info_player_start"
"BSP" "c:\program files\steam\steamapps\\sourcesdk\bin\vbsp.exe"
"Vis" "c:\program files\steam\steamapps\\sourcesdk\bin\vvis.exe"
"Light" "c:\program files\steam\steamapps\\sourcesdk\bin\vrad.exe"
"GameExeDir" "c:\program files\steam\steamapps\\half-life 2"
"MapDir" "c:\program files\steam\steamapps\\sourcesdk_content\hl2\mapsrc"
"BSPDir" "c:\program files\steam\steamapps\\half-life 2\hl2\maps"
"CordonTexture" "tools\toolsskybox"
"MaterialExcludeCount" "0"
}
}
"Counter-Strike: Source"
{
"GameDir" "c:\program files\steam\steamapps\\counter-strike source\cstrike"
"hammer"
{
"GameData0" "c:\program files\steam\steamapps\\sourcesdk\bin\cstrike.fgd"
"TextureFormat" "5"
"MapFormat" "4"
"DefaultTextureScale" "0.250000"
"DefaultLightmapScale" "16"
"GameExe" "c:\program files\steam\steamapps\\counter-strike source\hl2.exe"
"DefaultSolidEntity" "func_detail"
"DefaultPointEntity" "info_player_terrorist"
"BSP" "c:\program files\steam\steamapps\\sourcesdk\bin\vbsp.exe"
"Vis" "c:\program files\steam\steamapps\\sourcesdk\bin\vvis.exe"
"Light" "c:\program files\steam\steamapps\\sourcesdk\bin\vrad.exe"
"GameExeDir" "c:\program files\steam\steamapps\\counter-strike source"
"MapDir" "c:\program files\steam\steamapps\\sourcesdk_content\cstrike\mapsrc"
"BSPDir" "c:\program files\steam\steamapps\\counter-strike source\cstrike\maps"
"CordonTexture" "tools\toolsskybox"
"MaterialExcludeCount" "0"
}
}
"Half-Life 2: Deathmatch"
{
"GameDir" "c:\program files\steam\steamapps\\half-life 2 deathmatch\hl2mp"
"hammer"
{
"GameData0" "c:\program files\steam\steamapps\\sourcesdk\bin\hl2mp.fgd"
"TextureFormat" "5"
"MapFormat" "4"
"DefaultTextureScale" "0.250000"
"DefaultLightmapScale" "16"
"GameExe" "c:\program files\steam\steamapps\\half-life 2 deathmatch\hl2.exe"
"DefaultSolidEntity" "func_detail"
"DefaultPointEntity" "info_player_deathmatch"
"BSP" "c:\program files\steam\steamapps\\sourcesdk\bin\vbsp.exe"
"Vis" "c:\program files\steam\steamapps\\sourcesdk\bin\vvis.exe"
"Light" "c:\program files\steam\steamapps\\sourcesdk\bin\vrad.exe"
"GameExeDir" "c:\program files\steam\steamapps\\half-life 2 deathmatch"
"MapDir" "c:\program files\steam\steamapps\\sourcesdk_content\hl2mp\mapsrc"
"BSPDir" "c:\program files\steam\steamapps\\half-life 2 deathmatch\hl2mp\maps"
"CordonTexture" "tools\toolsskybox"
"MaterialExcludeCount" "0"
}
}
"Half-Life 2: Episode One"
{
"GameDir" "c:\program files\steam\steamapps\\half-life 2 episode one\episodic"
"hammer"
{
"GameData0" "c:\program files\steam\steamapps\\sourcesdk\bin\halflife2.fgd"
"TextureFormat" "5"
"MapFormat" "4"
"DefaultTextureScale" "0.250000"
"DefaultLightmapScale" "16"
"GameExe" "c:\program files\steam\steamapps\\half-life 2 episode one\hl2.exe"
"DefaultSolidEntity" "func_detail"
"DefaultPointEntity" "info_player_start"
"BSP" "c:\program files\steam\steamapps\\sourcesdk\bin\vbsp.exe"
"Vis" "c:\program files\steam\steamapps\\sourcesdk\bin\vvis.exe"
"Light" "c:\program files\steam\steamapps\\sourcesdk\bin\vrad.exe"
"GameExeDir" "c:\program files\steam\steamapps\\half-life 2 episode one"
"MapDir" "c:\program files\steam\steamapps\\sourcesdk_content\episodic\mapsrc"
"BSPDir" "c:\program files\steam\steamapps\\half-life 2 episode one\episodic\maps"
"CordonTexture" "tools\toolsskybox"
"MaterialExcludeCount" "0"
}
}
}
"SDKVersion" "2"
}You can add a game or edit what you need like texture default scale.
don't forgot to edit
I dislike using %steamdirectories% that's not workon all computer and may your environnement vars aren't set as well 
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