In order to resolve this issue, please, try the following:
1. Make sure that your computer meets the minimum system requirements;
2. Update the graphics card drivers;
3. Install the latest DirectX version;
4. Perform a clean boot;
5. Re-install the game client.
If none of the above resolved the issue, please submit a new ticket to our Customer Support service.
Please make sure to attach a screenshot of the error, the list of all running processes on your computer, and a DxDiag file.