Firstly, please make sure that your PC meets the The Witcher 2: Assassins of Kings system requirements
If the requirements are met please try the solutions below:
1. Reinstall your GPU drivers. To do so completely follow these steps:
2. Uninstall all of the Microsoft Visual C++ redistributables that you have installed.
Once it's done install the Microsoft Visual C++ redistributable packages from the link below starting from the oldest ones (skip the "arm" files). Launch all the executables as Administrator.
3. Disable all unneccessary apps before launching the game (especially apps with overlay) such as:
4. Please try launching The Witcher 2 in a clean boot mode. Here is how to perform clean boot - https://support.microsoft.com/en-us/kb/929135/
If none of the above will help, please report the issue to us, if there is any information or error code displayed please make sure to include it in the description.