Please do the following:
First, go to your Steam Games Library, right-click on King Arthur II, select Properties / Local Files / Verify integrity of game cache... - to retrieve any files deleted/missing
NOTE: If you are running Windows Vista or Windows 7, you may need to manually run secondary installers required by this game. (always right-click on the .exe file and choose: "Run as administrator" - even if you already have admin rights!)
also NOTE: If you are running Windows Vista or Windows 7, please completely exit Steam, and right-click on the shortcut which you use to launch Steam and select "Run as Administrator."
Browse to your King Arthur II installation folder (Usually C:\ Program Files \ Steam \ steamapps \ common \ kingarthurii \)
(If you have the game on Steam, make sure you are signed in to your account before launching the game.) Try to launch the game with the different Coretech exe files directly as an administrator (always right-click on the .exe file and choose: "Run as administrator" - even if you already have admin rights!).
If it did not help, exit Steam entirely.
Browse to your King Arthur II installation folder again. You will need to run the following installers:
...\steamapps\common\kingarthurii\InstallUtils\DirectX\DXSETUP.exe (right-click and choose: "Run as administrator")
...\steamapps\common\kingarthurii\InstallUtils\vcredist_x86_SP1.exe (right-click and choose: "Run as administrator")
...\steamapps\common\kingarthurii\InstallUtils\vcredist_x64_SP1.exe (right-click and choose: "Run as administrator")
and also run both WindowsMedia installers as an administrator.
Restart your computer and test the issue again.
If you continue to have difficulty, run this installer as well:
...\steamapps\common\common\kingarthurii\InstallUtils\PhysX_9.10.0513_SystemSoftware.exe (right-click and choose: "Run as administrator")
Then, restart your computer once more and test the issue again.
Please also check your anti-virus or firewall and add an exception for the game if necessary, sometimes these programs are blocking some games.
There's also a list of solutions that other players of King Arthur II created, you might want to try them too:
http://bit.ly/LYDMqP
Also, this might help if nothing of the above solved the problem:
- download "cff explorer 7"
- open the .exe-files for King Arthur II with cff explorer (King ArthurII.exe, CoreTech2_x86.exe, CoreTech2_x86_10.exe, CoreTech2_x86_11.exe)
- Go to NT Headers / File Header, click on "click here" (lower right)
- check the box "app can handle >2GB