The most likely cause is that the installer program was corrupted. Download a new copy.
Download the client zip from one of the links here, and then put the gesource folder in
Steam/steamapps/sourcemods. Note that you can only install Source mods to your main Steam library (under the location which Steam itself is installed). For more information, check the installation guide.
This issue is typically observed when running the game at very high resolutions, i.e. 4K. Try setting the display resolution to 1080p or lower:
-w 1920 -h 1080
Install the 32-bit (x86) version of the Visual Studio C++ 2012 redistributable.
This indicates that the .dll files for GoldenEye: Source are corrupt or missing.
Validate your local files for Source SDK Base 2007. You can either:
Click here to validate through Steam, or validate manually through Steam: