Here is a copy of the ticket that has yet to be answered by Valve.
I am needing help getting left 4 dead 2 to install. I have restarted steam to install any new updates, I verified integrity of the game cache, I defragged the files, I restarted my machine, then I uninstalled it and tried to reinstall and it just sits on creating game cache and then tells me the servers are too busy to handle my request over and over again. Please help me resolve this or let me know if there is a known issue.
My system specs are: i5-3570k Asus p8z77-v gigabyte 7950 3gb corsair 1600 8gb ram win 7 64 bit install drive is a WD 1tb caviar black