Left 4 Dead 2 install problem! (no autorun.exe)

Hi a few hours ago I bought a retail copy of Left 4 Dead 2 and went to install it, the autorun only allowed me to view files rather than starting the install so I clicked the setup which installs Steam then registered the game but, then its downloading the full bloody game when I've got the disc and Steam doesn't give an option to install from disc!
I really don't see a point in downloading the game when I've got the install disc here. I cannot see the autorun.exe and I never have this problem on any other game! The only antivirus i have is Microsoft Security Essentials I just need help in installing the game without this download which has slowed down after 1gb of 7gb giving me 1 day to completion!

Okay I've fixed the problem- I needed to remove disc and exit Steam then reinserted disc and clicked setup again and steam gave option which is installing right now :)

archie123 said:

yeah i had the same problem with modern warfare 2 , bought the disk tried to install and steam started downloading it!! cant rememebr how i sorted it though

No problem I got it sorted now but it still needed to download after 83% for some reason :s