Can't Install Norton Internet Security 4 on my Macbook

Hi There,

 

I have a Macbook Air with up to date software version 10.8.2. I have purchased and am trying to download file: Norton_Internet_Security_4_Mac_EN.dmg, but it won’t download. The installer icon just bounces up and down, and when I click on it nothing happens.

 

I have just installed two other applications with no problems, and cleaned up my hard drive so that I have tons of free space.

 

Any ideas?

 

Thank you, 

Heath