I'm have experienced the same error as well. To counter it, you will need to manually open up "Counter-strike source shared.gcf" in your "Steamapps" foldier using a program called "GCFSCAPE".
Export the materials and models folders from this .gcf into your main Garry's mod directory where the "materials" and "models" folders are located. Overwrite both folders (do not delete and then replace them). You should be fine now.
Export the materials and models folders from this .gcf into your main Garry's mod directory where the "materials" and "models" folders are located. Overwrite both folders (do not delete and then replace them). You should be fine now.
I used this option, As i use GFCSCAPE often. It worked perfectly. Thanks Silverstream! And all of you for the help! Now, to begin TTT mapping....