I had just reformatted and I made a C:\ drive for programs and windows and a D:\ drive for games. I had made the mistake of installing steam to D:\ and not D:\Steam\ so all the steam files were clustered in the D:\ drive. So I went into program files and uninstalled it for a second go at installing it to the right location. That's when during the installation I had received this error. "ERROR 1303: THE INSTALLATION HAS INSUFFICIENT PRIVILEGES TO ACCESS THE DIRECTORY..." I had tried many many things... Only one worked. I had to reformat the D:\ drive! Luckily nothing was on it so if you have files back them up. Go to my computer and left click the D:\ drive and click format.