A simple fix for me: 1) To get rid of the error you get when compiling a map, change to this: 2) Now CS:S looks for custom materials/models/sounds in one folder while Hammer looks for it in another. So you might see your stuff in game but not in hammer, etc. Simple fix for me was to simply symlink them to each other. If you don't want to use the command prompt, simply get a program like this. Then do the following. Choose your materials/models/sound folder from the old CSS folder, right click on it and choose Pick Link Source: And then go into your new CSS folder and do the following: That's all you need to do. Granted, if you make new custom things, you'll have to link them as well if you don't want to place them directly into the new css folder. Has worked fine for me just like steampipe never happened. Hope this helps.