I downloaded hl2, css and hl2:ep1 today to play gmod, but when I loaded gmod up it just stuck at the first loading screen for ages. I have tried to defrag and verify integrity but no cigar. I have played before and have recently formatted to get this problem.

64bit Windows 7 Ultimate
4GB DDR3 RAM
AMD x4 955 3.2ghz OC to 3.8ghz
AMD 6870 1GB

Thanks :D