Setup won't run - can't install download

hi,

 

i recently attempted to install norton internet security into another one of my personal laptops, but when i clicked to run it after the download, i got this message instead: 

 

"download manager requires administrator privileges to install download"

 

i've checked, and since there's only one user registered on this computer, i'm the administrator. any ideas on how i can fix this?

 

thanks :)