HL2 and CS:S works just fine but ever since a certain steam update was applied no mod that I make will work. Maybe if I download a later version of a third party mod it will work but mainly I'm just trying to run mine. When I start it up it appears to load and does the whole black screen thing but then it quits and says it has an 'Engine Error' "Could not load library client". I'm guessing it may have something to do with one of those major updates, like the one where it said you have to change that SteamAppId number in the gameinfo txt file. Well I changed it but after that it never seemed to work.