The file may be one of the following.
Missing
Corrupt
Or have the wrong name
Make sure when you unzip the file, EVERYTHING gets unzipped.
You may have to go in and unzip more.
DATA1.CAB is usually the kind of file that has everything important in it. So make sure it exisits.
ALSO, when you unzip the file, try and unzip it to a folder with minimal sublevels. eg.
C:\photoshop install
And run it from there.
ALSO try using different extraction methods:
Extract Here
Extract Files...
Extract to Folder
Using Extract here often is the most reliable to copy to ZIP to C:\photoshop (Create it if it doesn't already exist) and then use Extract here.
ALSO try using different Software to extract it
WinRAR & PowerArchiver will often do the job where the other fails.
Finally... Download a working one if none of the above helps.