Since many of you decide to uninstall and reinstall game to solve unexplained problems here are a couple of tips.

First after installation always make sure that no files have been remained in former napoleon total war directory. If there are delete everything manually. Have in mind that uninstallation removes only offciall game files that were installed in first place, so if you have added mod files these will remain after uninstallation. And perhaps the reason of your problem...

Then after you have uninstalled everything:

1. Start Steam and login.
2. Insert the first disc into your computer.
3. Close Steam (Steam > Exit).
4. Press Windows Key + R to open Run
5. In the Run window type:

Code:
"C:\Program Files(x86)\Steam\Steam.exe" -install E:
where E is CD/DVD drive you are installing from. Replace if necessary. C:\Program Files(x86)\Steam is the default location so replace it with yours if you have it elsewhere.

7. Press OK. Steam will launch and ask you to sign in if you do not have your password saved. Your installation should continue from the disc.