1) Disable UAC on Windows 7 And Windows Vista
2) Extract To Short Paths Like C:/Games Or D:/Games
3) Go To The Extracted Folder And Run the SETUP.bat File
4) Wait Till Finished Rebuilding. Then Start The Game From Your Desktop.
Compressed Game Is 1.97GB
After Decompression Is 8.03GB
# Change Your Ingame Name And Language With "L4D2 Control Panel"
# If you have any sound trouble, like Crackling sounds in between the game or the audio doesn't syncs or similar to that. All you have to do is :
-> Open Console and type the following Command
And then wait for few mins(10-15mins), Exit and Restart the game.