there is a temporary fix(way around it)
go to C:Program FilesSteamSteamAppsusernamecounter-strike sourcecstrike and open the gameinfo.txt file (in notepad)
edit the line that says
ToolsAppId 211 // Tools will load this (ie: source SDK caches) to get things like materialsdebug, materialseditor, etc.
and remove the word tools from ToolsAppId
so it should read
AppId 211 // Tools will load this (ie: source SDK caches) to get things like materialsdebug, materialseditor, etc.
another error pops up about the .dll file but at least hammer opens :