Please verify the installer you're using was completely downloaded and not corrupted by checking its digital signature.
If the installer is correct, please try running it again and allowing it to restart the machine at the end, if asks to.
If things are still wrong after that, the most likely cause is probably antivirus blocking the new binaries from being written into the directory. Please check the antivirus logs and try disabling the virus scanner before running the installer. (Of course, only do this if the installer's digital signature is valid, else it could be a modified installer from someone else.) This has caused the above problem for a couple of people before.