|Exit Code: 20 - install source path does not exist||Install source files are missing.||Reextract or copy the contents of the installer.|
See: Installation, launch log errors | CS5, CS5.5, CS6, CCM
Although my install generated an Error(20) - not Exit Code: 20 - I was able to resolve the problem be relocating the install files. I had them on a network server. By copying them to my local drive, the install was successful. No need to download again.