Just because you played to a certain point doesn't mean they haven't become corrupted or made a bad call to resources due to errors in installation.
And driver installs are quicker and easier than backing up your save, uninstalling, reinstalling, and repatching the game. CoP has many known errors with DirectX and graphics drivers because it is a base DX 9.0 engine with DX 10 and 11 effects tacked on without thorough testing for performance and compatibility. That's just compounded by the poor architecture of Windows 8's kernel.
Quicker and easier, and you wont lose all your progress. IF these don't work, it is a bad game install. Nuke it, clean out all folders and reinstall clean.