If you download the Neat Image installer (NeatSetup.exe), start it and receive an error message about "corrupted file", that means the file has not been completely downloaded by the web browser (or another download software you use).

Possible solutions:

• Clear the browser cache (to not let the browser re-use the locally cached incomplete version of the file; otherwise it will not actually re-download from the website when you try to re-download),
  restart the browser and then try to re-download the file.
  
  
  • To clear the cache, in Internet Explorer, go to menu Tools | Internet options | Temporary Internet files | Delete Files... | OK
    
    
    
    
• Download the installer using another web browser or download software (software that is able to resume incomplete downloads tends to be more efficient)
  
  
• Download a ZIP version of the installer when available