I'm encountering this problem now and the posted solutions are not working for me. I had been running Windows 8.1 and just bought a new laptop running Windows 10. I tried the link for downloading the DirectX End-User runtime and it seems to be deprecated. I searched online to try and find the dll files needed and placed them in Windows/System32 and it made no difference (except that now the error messages show up in a different order). I tried this method of installing Rift and it made no difference. I tried transferring the dll files from my old laptop onto my new one and it made no difference. Is there anything else I can try?