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. Reinstall (uninstall and install them back) all of the Microsoft Visual C++ from the links below:
Both the 32-bit and the 64-bit versions of the programs below will work on 64-bit versions of Windows.
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.